crypto(3)

NAME
crypto - Crypto Functions

DESCRIPTION

This module provides a set of cryptographic functions.

    • Hash functions - SHA1, SHA2
        Secure Hash Standard (FIPS PUB180-4)
    SHA3
        SHA-3 Standard: Permutation-Based Hash and Extendable-Output Functions (FIPS PUB 202)
    BLAKE2
        BLAKE2 — fast secure hashing
    SM3
        The SM3 Hash Function (GM/T 0004-2012)
    MD5
        The MD5 Message Digest Algorithm (RFC 1321)
    MD4
        The MD4 Message Digest Algorithm (RFC 1320)

    • MACs - Message Authentication Codes - Hmac functions
        Keyed-Hashing for Message Authentication (RFC 2104)
    Cmac functions
        The AES-CMAC Algorithm (RFC 4493)
    POLY1305
        ChaCha20 and Poly1305 for IETF Protocols (RFC 7539)
Symmetric Ciphers
    DES, 3DES and AES
        Block Cipher Techniques (NIST)
    Blowfish
        Fast Software Encryption, Cambridge Security Workshop Proceedings (December 1993), Springer-Verlag, 1994, pp. 191-204.
    Chacha20
        ChaCha20 and Poly1305 for IETF Protocols (RFC 7539)
    Chacha20_poly1305
        ChaCha20 and Poly1305 for IETF Protocols (RFC 7539)
    SM4
        The SM4 Block Cipher Algorithm

    • Modes - ECB, CBC, CFB, OFB and CTR
        Recommendation for Block Cipher Modes of Operation: Methods and Techniques (NIST SP 800-38A)
    GCM
        Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC (NIST SP 800-38D)
    CCM
        Recommendation for Block Cipher Modes of Operation: The CCM Mode for Authentication and Confidentiality (NIST SP 800-38C)

    • Asymmetric Ciphers - Public Key Techniques - RSA
        PKCS #1: RSA Cryptography Specifications (RFC 3447)
    DSS
        Digital Signature Standard (DSS) (FIPS 186-4)
    ECDSA
        Elliptic Curve Digital Signature Algorithm (ECDSA)
    SRP
        The SRP Authentication and Key Exchange System (RFC 2945)

NOTE: The actual supported algorithms and features depends on their availability in the actual libcrypto used. See the crypto (App) about dependencies. Enabling FIPS mode will also disable algorithms and features.

The CRYPTO User's Guide has more information on FIPS, Engines and Algorithm Details like key lengths.

  Exceptions

Atoms - the older style

The exception error:badarg signifies that one or more arguments are of wrong data type, or are otherwise badly formed.

The exception error:notsup signifies that the algorithm is known but is not supported by current underlying libcrypto or explicitly disabled when building that.

For a list of supported algorithms, see supports(ciphers).

3-tuples - the new style

The exception is:

    error:{Tag, C_FileInfo, Description}
    Tag = badarg | notsup | error
    C_FileInfo = term()    % Usually only useful for the OTP maintainer
    Description = string() % Clear text, sometimes only useful for the OTP maintainer

The exception tags are: badarg
    Signifies that one or more arguments are of wrong data type or are otherwise badly formed.
notsup
    Signifies that the algorithm is known but is not supported by current underlying libcrypto or explicitly disabled when building that one.
error
    An error condition that should not occur, for example a memory allocation failed or the underlying cryptolib returned an error code, for example "Can't initialize context, step 1". Those text usually needs searching the C-code to be understood.

Usually there are more information in the call stack about which argument caused the exception and what the values where.

To catch the exception, use for example:

    try crypto:crypto_init(Ciph, Key, IV, true)
        catch
            error:{Tag, _C_FileInfo, Description} ->
                do_something(......)
             .....
    end

DATA TYPES

blake2() :: blake2b | blake2s.
cipher() :: cipher_no_iv() | cipher_iv() | cipher_aead().
cipher_aead() :: aes_128_ccm | aes_192_ccm | aes_256_ccm | aes_ccm | aes_128_gcm | aes_192_gcm | aes_256_gcm | aes_gcm | sm4_gcm | sm4_ccm | chacha20_poly1305.

    Ciphers known by the CRYPTO application.

    Note that this list might be reduced if the underlying libcrypto does not support all of them.
cipher_iv() :: aes_128_cbc | aes_192_cbc | aes_256_cbc | aes_cbc | aes_128_ofb | aes_192_ofb | aes_256_ofb | aes_128_cfb128 | aes_192_cfb128 | aes_256_cfb128 | aes_cfb128 | aes_128_cfb8 | aes_192_cfb8 | aes_256_cfb8 | aes_cfb8 | aes_128_ctr | aes_192_ctr | aes_256_ctr | aes_ctr | sm4_cbc | sm4_ofb | sm4_cfb | sm4_ctr | blowfish_cbc | blowfish_cfb64 | blowfish_ofb64 | chacha20 | des_ede3_cbc | des_ede3_cfb | des_cbc | des_cfb | rc2_cbc.
cipher_no_iv() :: aes_128_ecb | aes_192_ecb | aes_256_ecb | aes_ecb | blowfish_ecb | des_ecb | sm4_ecb | rc4.
cmac_cipher_algorithm() :: aes_128_cbc | aes_192_cbc | aes_256_cbc | aes_cbc | blowfish_cbc | des_cbc | des_ede3_cbc | rc2_cbc.
compatibility_only_hash() :: md5 | md4.

    The compatibility_only_hash/0 algorithms are recommended only for compatibility with existing applications.
crypto_integer() :: binary() | integer().
crypto_opt() :: {encrypt, boolean()} | {padding, padding()}.

    Selects encryption ({encrypt,true}) or decryption ({encrypt,false}).
crypto_opts() :: boolean() | [crypto_opt()].
-opaque crypto_state()
cryptolib_padding() :: none | pkcs_padding.

    The cryptolib_padding are paddings that may be present in the underlying cryptolib linked to the Erlang/OTP crypto app.

    For OpenSSL, see the OpenSSL documentation. and find EVP_CIPHER_CTX_set_padding() in cryptolib for your linked version.
dh_params() :: [key_integer()].

        dh_params() = [P, G] | [P, G, MaxPrivateKeyBitLength]
dh_private() :: key_integer().
dh_public() :: key_integer().
dss_digest_type() :: sha1() | sha2().
dss_private() :: [key_integer()].

        dss_public() = [P, Q, G, Y]

    Where P, Q and G are the dss parameters and Y is the public key.

        dss_private() = [P, Q, G, X]

    Where P, Q and G are the dss parameters and X is the private key.
dss_public() :: [key_integer()].
ec_basis() :: {tpbasis, K :: non_neg_integer()} | {ppbasis, K1 :: non_neg_integer(), K2 :: non_neg_integer(), K3 :: non_neg_integer()} | onbasis.

    Curve definition details.
ec_characteristic_two_field() :: {characteristic_two_field, M :: integer(), Basis :: ec_basis()}.
ec_curve() :: {A :: binary(), B :: binary(), Seed :: none | binary()}.

    Parametric curve definition.
ec_explicit_curve() :: {Field :: ec_field(), Curve :: ec_curve(), BasePoint :: binary(), Order :: binary(), CoFactor :: none | binary()}.
ec_field() :: ec_prime_field() | ec_characteristic_two_field().
ec_named_curve() :: brainpoolP160r1 | brainpoolP160t1 | brainpoolP192r1 | brainpoolP192t1 | brainpoolP224r1 | brainpoolP224t1 | brainpoolP256r1 | brainpoolP256t1 | brainpoolP320r1 | brainpoolP320t1 | brainpoolP384r1 | brainpoolP384t1 | brainpoolP512r1 | brainpoolP512t1 | c2pnb163v1 | c2pnb163v2 | c2pnb163v3 | c2pnb176v1 | c2pnb208w1 | c2pnb272w1 | c2pnb304w1 | c2pnb368w1 | c2tnb191v1 | c2tnb191v2 | c2tnb191v3 | c2tnb239v1 | c2tnb239v2 | c2tnb239v3 | c2tnb359v1 | c2tnb431r1 | ipsec3 | ipsec4 | prime192v1 | prime192v2 | prime192v3 | prime239v1 | prime239v2 | prime239v3 | prime256v1 | secp112r1 | secp112r2 | secp128r1 | secp128r2 | secp160k1 | secp160r1 | secp160r2 | secp192k1 | secp192r1 | secp224k1 | secp224r1 | secp256k1 | secp256r1 | secp384r1 | secp521r1 | sect113r1 | sect113r2 | sect131r1 | sect131r2 | sect163k1 | sect163r1 | sect163r2 | sect193r1 | sect193r2 | sect233k1 | sect233r1 | sect239k1 | sect283k1 | sect283r1 | sect409k1 | sect409r1 | sect571k1 | sect571r1 | wtls1 | wtls10 | wtls11 | wtls12 | wtls3 | wtls4 | wtls5 | wtls6 | wtls7 | wtls8 | wtls9.
ec_prime_field() :: {prime_field, Prime :: integer()}.
ecdh_params() :: ec_named_curve() | edwards_curve_dh() | ec_explicit_curve().
ecdh_private() :: key_integer().
ecdh_public() :: key_integer().
ecdsa_digest_type() :: sha1() | sha2().
ecdsa_params() :: ec_named_curve() | ec_explicit_curve().
ecdsa_private() :: key_integer().
ecdsa_public() :: key_integer().
eddsa_params() :: edwards_curve_ed().
eddsa_private() :: key_integer().
eddsa_public() :: key_integer().
edwards_curve_dh() :: x25519 | x448.
edwards_curve_ed() :: ed25519 | ed448.

    Note that some curves are disabled if FIPS is enabled.
engine_cmnd() :: {unicode:chardata(), unicode:chardata()}.

    Pre and Post commands for engine_load/3 and /4.
engine_key_ref() :: #{engine := engine_ref(), key_id := key_id(), password => password(), term() => term()}.
engine_method_type() :: engine_method_rsa | engine_method_dsa | engine_method_dh | engine_method_rand | engine_method_ecdh | engine_method_ecdsa | engine_method_ciphers | engine_method_digests | engine_method_store | engine_method_pkey_meths | engine_method_pkey_asn1_meths | engine_method_ec.
engine_ref() :: term().

    The result of a call to engine_load/3.
hash_algorithm() :: sha1() | sha2() | sha3() | sha3_xof() | blake2() | ripemd160 | sm3 | compatibility_only_hash().
-opaque hash_state()
hash_xof_algorithm() :: sha3_xof().
hmac_hash_algorithm() :: sha1() | sha2() | sha3() | sm3 | compatibility_only_hash().
kem() :: mlkem512 | mlkem768 | mlkem1024.

    Key encapsulation mechanisms.
key_id() :: string() | binary().

    Identifies the key to be used. The format depends on the loaded engine. It is passed to the ENGINE_load_(private|public)_key functions in libcrypto.
key_integer() :: integer() | binary().

    Always binary/0 when used as return value
-opaque mac_state()

    Contexts with an internal state that should not be manipulated but passed between function calls.
mldsa() :: mldsa44 | mldsa65 | mldsa87.
mldsa_private() :: {seed | expandedkey, binary()}.
mldsa_public() :: binary().
otp_padding() :: zero | random.

    Erlang/OTP adds a either padding of zeroes or padding with random bytes.
padding() :: cryptolib_padding() | otp_padding().

    This option handles padding in the last block. If not set, no padding is done and any bytes in the last unfilled block is silently discarded.
password() :: string() | binary().

    The password of the key stored in an engine.
pk_encrypt_decrypt_algs() :: rsa.

    Algorithms for public key encrypt/decrypt. Only RSA is supported.
pk_encrypt_decrypt_opts() :: [rsa_opt()] | rsa_compat_opts().
pk_sign_verify_algs() :: rsa | dss | ecdsa | eddsa | mldsa() | slh_dsa().

    Algorithms for sign and verify.
pk_sign_verify_opts() :: [rsa_sign_verify_opt()].
rand_cache_seed() :: nonempty_improper_list(non_neg_integer(), binary()).
rsa_compat_opts() :: [{rsa_pad, rsa_padding()}] | rsa_padding().

    Those option forms are kept only for compatibility and should not be used in new code.
rsa_digest_type() :: sha1() | sha2() | md5 | ripemd160.
rsa_opt() :: {rsa_padding, rsa_padding()} | {signature_md, atom()} | {rsa_mgf1_md, sha} | {rsa_oaep_label, binary()} | {rsa_oaep_md, sha}.
rsa_padding() :: rsa_pkcs1_padding | rsa_pkcs1_oaep_padding | rsa_x931_padding | rsa_no_padding.

    Options for public key encrypt/decrypt. Only RSA is supported.

    WARNING: The RSA options are experimental. The exact set of options and there syntax may be changed without prior notice.
rsa_params() :: {ModulusSizeInBits :: integer(), PublicExponent :: key_integer()}.

        rsa_public() = [E, N]

        rsa_private() = [E, N, D] | [E, N, D, P1, P2, E1, E2, C]

    Where E is the public exponent, N is public modulus and D is the private exponent. The longer key format contains redundant information that will make the calculation faster. P1 and P2 are first and second prime factors. E1 and E2 are first and second exponents. C is the CRT coefficient. The terminology is taken from RFC 3447.
rsa_private() :: [key_integer()].
rsa_public() :: [key_integer()].
rsa_sign_verify_opt() :: {rsa_padding, rsa_sign_verify_padding()} | {rsa_pss_saltlen, integer()} | {rsa_mgf1_md, sha2()}.
rsa_sign_verify_padding() :: rsa_pkcs1_padding | rsa_pkcs1_pss_padding | rsa_x931_padding | rsa_no_padding.

    Options for sign and verify.

    WARNING: The RSA options are experimental. The exact set of options and there syntax may be changed without prior notice.
sha1() :: sha.
sha2() :: sha224 | sha256 | sha384 | sha512 | sha512_224 | sha512_256.
sha3() :: sha3_224 | sha3_256 | sha3_384 | sha3_512.
sha3_xof() :: shake128 | shake256.
slh_dsa() :: slh_dsa_shake_128s | slh_dsa_shake_128f | slh_dsa_sha2_128s | slh_dsa_sha2_128f | slh_dsa_shake_192s | slh_dsa_shake_192f | slh_dsa_sha2_192s | slh_dsa_sha2_192f | slh_dsa_shake_256s | slh_dsa_shake_256f | slh_dsa_sha2_256s | slh_dsa_sha2_256f.
slh_dsa_private() :: binary().
slh_dsa_public() :: binary().
srp_comp_params() :: {user, srp_user_comp_params()} | {host, srp_host_comp_params()}.
srp_gen_params() :: {user, srp_user_gen_params()} | {host, srp_host_gen_params()}.
srp_host_comp_params() :: [binary() | atom()].

    Where Verifier is v, Generator is g and Prime is N, DerivedKey is X, and Scrambler is u (optional will be generated if not provided) from SRP design Version = '3' | '6' | '6a'
srp_host_gen_params() :: [binary() | atom() | list()].
srp_private() :: key_integer().

        srp_public() = key_integer()

    Where is A or B from SRP design

        srp_private() = key_integer()

    Where is a or b from SRP design
srp_public() :: key_integer().
srp_user_comp_params() :: [binary() | atom()].
srp_user_gen_params() :: [binary() | atom() | list()].

FUNCTIONS

bytes_to_integer(binary()) -> integer().

    Convert binary representation, of an integer, to an Erlang integer.
cipher_info(Type) -> Result when Type :: cipher(), Result :: #{key_length := integer(), iv_length := integer(), block_size := integer(), mode := CipherModes, type := undefined | integer(), prop_aead := boolean()}, CipherModes :: undefined | cbc_mode | ccm_mode | cfb_mode | ctr_mode | ecb_mode | gcm_mode | ige_mode | ocb_mode | ofb_mode | wrap_mode | xts_mode.

    Get information about a cipher algorithm.

    Returns a map with information about block size, key length, IV length, aead support and possibly other properties of the cipher algorithm in question.

    NOTE: The ciphers aes_cbc, aes_cfb8, aes_cfb128, aes_ctr, aes_ecb, aes_gcm and aes_ccm has no keylength in the Type as opposed to for example aes_128_ctr. They adapt to the length of the key provided in the encrypt and decrypt function. Therefore it is impossible to return a valid keylength in the map. Always use a Type with an explicit key length,

    For a list of supported cipher algorithms, see supports(ciphers).
compute_key(Type, OthersPublicKey, MyPrivateKey, Params) -> SharedSecret when Type :: dh | ecdh | eddh | srp, SharedSecret :: binary(), OthersPublicKey :: dh_public() | ecdh_public() | srp_public(), MyPrivateKey :: dh_private() | ecdh_private() | {srp_public(), srp_private()}, Params :: dh_params() | ecdh_params() | srp_comp_params().

    Compute the shared secret from the private key and the other party's public key.

    See also public_key:compute_key/2.

    Uses the 3-tuple style for error handling.
crypto_final(State) -> FinalResult when State :: crypto_state(), FinalResult :: binary().

    Finalize a streaming encryptions or decryptions operation and delivers the final bytes of the final block.

    The data returned from this function may be empty if no padding was enabled in crypto_init/3 or crypto_init/4.

    Uses the 3-tuple style for error handling.
crypto_get_data(State) -> Result when State :: crypto_state(), Result :: map().

    Return information about a crypto_state/0.

    The information returned is a map, which currently contains at least: size
        The number of bytes encrypted or decrypted so far.
    padding_size
        After a call to crypto_final/1 it contains the number of bytes padded. Otherwise 0.
    padding_type
        The type of the padding as provided in the call to crypto_init/3 or crypto_init/4.
    encrypt
        Is true if encryption is performed. It is false otherwise.

    Uses the 3-tuple style for error handling.
crypto_init(Cipher, Key, FlagOrOptions) -> State when Cipher :: cipher_no_iv(), Key :: iodata(), FlagOrOptions :: crypto_opts() | boolean(), State :: crypto_state().

    Initialize the state for a streaming encryption or decryption operation.

    Equivalent to the call crypto_init(Cipher, Key, <<>>, FlagOrOptions). It is intended for ciphers without an IV (nounce).

    Uses the 3-tuple style for error handling.
crypto_init(Cipher, Key, IV, FlagOrOptions) -> State when Cipher :: cipher_iv(), Key :: iodata(), IV :: iodata(), FlagOrOptions :: crypto_opts(), State :: crypto_state().

    Initialize the state for a streaming encryptions or decryptions operation.

    The returned state should be used as argument to crypto_update/2 and crypto_final/1 to do the actual encryption or decryption.

    If IV = <<>>, no IV is used. This is intended for ciphers without an IV (nounce). See crypto_init/3.

    For encryption, set the FlagOrOptions to true or [{encrypt,true}]. For decryption, set it to false or [{encrypt,false}].

    Padding could be enabled with the option {padding,Padding}. The cryptolib_padding enables pkcs_padding or no padding (none). The paddings zero or random fills the last part of the last block with zeroes or random bytes. If the last block is already full, nothing is added.

    In decryption, the cryptolib_padding removes such padding, if present. The otp_padding is not removed - it has to be done elsewhere.

    If padding is {padding,none} or not specified and the total data from all subsequent crypto_updates does not fill the last block fully, that last data is lost. In case of {padding,none} there will be an error in this case. If padding is not specified, the bytes of the unfilled block is silently discarded.

    The actual padding is performed by crypto_final/1.

    For blocksizes call cipher_info/1.

    Uses the 3-tuple style for error handling.

    See examples in the User's Guide.
crypto_one_time(Cipher, Key, Data, FlagOrOptions) -> Result when Cipher :: cipher_no_iv(), Key :: iodata(), Data :: iodata(), FlagOrOptions :: crypto_opts() | boolean(), Result :: binary().

    Do a complete encrypt or decrypt of the full text.

    As crypto_one_time/5 but for ciphers without IVs.

    Uses the 3-tuple style for error handling.
crypto_one_time(Cipher, Key, IV, Data, FlagOrOptions) -> Result when Cipher :: cipher_iv(), Key :: iodata(), IV :: iodata(), Data :: iodata(), FlagOrOptions :: crypto_opts() | boolean(), Result :: binary().

    Do a complete encrypt or decrypt of the full text.

    Argument Data is the text to be encrypted or decrypted.

    For encryption, set the FlagOrOptions to true. For decryption, set it to false. For setting other options, see crypto_init/4.

    Uses the 3-tuple style for error handling.

    See examples in the User's Guide.
crypto_one_time_aead(State, IV, InText, AAD) -> Result when State :: crypto_state(), IV :: iodata(), InText :: iodata(), AAD :: iodata(), Result :: EncryptResult | DecryptResult, EncryptResult :: binary(), DecryptResult :: binary() | error.

    Do a complete encrypt or decrypt with an AEAD cipher of the full text.

    Similar to 'crypto_one_time_aead/7' but uses the handle from 'crypto_one_time_aead_init/4'.

    Appends the tag of the specified 'TagLength' to the end of the encrypted data, when doing encryption. Strips the tag from the end of 'InText' and verifies it when doing decryption.
crypto_one_time_aead(Cipher, Key, IV, InText, AAD, EncFlag :: true) -> Result when Cipher :: cipher_aead(), Key :: iodata(), IV :: iodata(), InText :: iodata(), AAD :: iodata(), Result :: EncryptResult, EncryptResult :: {OutCryptoText, OutTag}, OutCryptoText :: binary(), OutTag :: binary().

    Do a complete encrypt with an AEAD cipher of the full text with the default tag length.

    Equivalent to crypto_one_time_aead(Cipher, Key, IV, InText, AAD, TagLength, true) where TagLength is the default tag length for the given Cipher.
crypto_one_time_aead(Cipher, Key, IV, InText, AAD, TagOrTagLength, EncFlag) -> Result when Cipher :: cipher_aead(), Key :: iodata(), IV :: iodata(), InText :: iodata(), AAD :: iodata(), TagOrTagLength :: EncryptTagLength | DecryptTag, EncryptTagLength :: non_neg_integer(), DecryptTag :: iodata(), EncFlag :: boolean(), Result :: EncryptResult | DecryptResult, EncryptResult :: {OutCryptoText, OutTag}, DecryptResult :: OutPlainText | error, OutCryptoText :: binary(), OutTag :: binary(), OutPlainText :: binary().

    Do a complete encrypt or decrypt with an AEAD cipher of the full text.

    For encryption, set the EncryptFlag to true and set the TagOrTagLength to the wanted size (in bytes) of the tag, that is, the tag length. If the default length is wanted, the crypto_one_time_aead/6 form may be used.

    For decryption, set the EncryptFlag to false and put the tag to be checked in the argument TagOrTagLength.

    WARNING: The length of the tag at decryption is not checked by the function. It is the caller's responsibility to ensure that the length of the tag matches the length of the tag used when the data was encrypted. Otherwise the decryption may succeed if the given tag only matches the start of the proper tag.

    Additional Authentication Data (AAD) is plaintext data that will not be encrypted, but will be covered by authenticity protection. It should be provided through the AAD argument, but can be an empty binary as well (<<>>) if not needed. In that case, a plain AE (Authenticated Encryption) is performed instead of AEAD (Authenticated Encryption with Associated Data). This function only supports ciphers that can be used both with and without AAD.

    Uses the 3-tuple style for error handling.

    See examples in the User's Guide.
crypto_one_time_aead_init(Cipher, Key, TagLength, EncFlag) -> Result when Cipher :: cipher_aead(), Key :: iodata(), TagLength :: non_neg_integer(), EncFlag :: boolean(), Result :: crypto_state().

    Initializes AEAD cipher.

    Similar to 'crypto_one_time_aead/7' but only does the initialization part, returns a handle that can be used with 'crypto_one_time_aead/4' serveral times.
crypto_update(State, Data) -> Result when State :: crypto_state(), Data :: iodata(), Result :: binary().

    Add data to a streaming encryption or decryption operation.

    If the part is less than a number of full blocks, only the full blocks (possibly none) are encrypted or decrypted and the remaining bytes are saved to the next crypto_update operation. The State should be created with crypto_init/3 or crypto_init/4.

    Uses the 3-tuple style for error handling.

    See examples in the User's Guide.
decapsulate_key(Type, MyPrivKey, EncapSecret) -> Secret when Type :: kem(), MyPrivKey :: binary(), EncapSecret :: binary(), Secret :: binary().

    Regenerate shared secret from encapsulated secret and private key.

    Returns a shared secret for encryption/decryption by local party.

    Supported encapsulation methods can be obtained with supports(kems).
ec_curve(CurveName) -> ExplicitCurve when CurveName :: ec_named_curve(), ExplicitCurve :: ec_explicit_curve().

    Return the defining parameters of a elliptic curve.
ec_curves() -> [EllipticCurve] when EllipticCurve :: ec_named_curve() | edwards_curve_dh() | edwards_curve_ed().

    Return all supported named elliptic curves.
enable_fips_mode(Enable) -> Result when Enable :: boolean(), Result :: boolean().

    Deprecated: crypto:enable_fips_mode/1 is deprecated; use config parameter fips_mode

    Enable or disable FIPs mode.

    Argument Enable should be true to enable and false to disable FIPS mode. Returns true if the operation was successful or false otherwise.

    Note that to enable FIPS mode successfully, OTP must be built with the configure option --enable-fips, and the underlying libcrypto must also support FIPS.

    See also info_fips/0.
encapsulate_key(Type, OthersPublicKey) -> {Secret, EncapSecret} when Type :: kem(), OthersPublicKey :: binary(), Secret :: binary(), EncapSecret :: binary().

    Generate encapsulated shared secret from the other party's public key.

    Returns both a shared secret for encryption/decryption by local party and an encapsulated format of the same secret to be safely sent to the other party. With its private key, the other party can decapsulate the received secret (with decapsulate_key/3 for example) to regenerate the same shared secret.

    Supported encapsulation methods can be obtained with supports(kems).
engine_add(Engine) -> Result when Engine :: engine_ref(), Result :: ok | {error, Reason :: term()}.

    Add the engine to OpenSSL's internal list.

    The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.
engine_by_id(EngineId) -> Result when EngineId :: unicode:chardata(), Result :: {ok, Engine :: engine_ref()} | {error, Reason :: term()}.

    Get a reference to an already loaded engine with EngineId. An error tuple is returned if the engine cannot be unloaded.

    The function raises a error:badarg if the parameter is in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

    See also the chapter Engine Load in the User's Guide.
engine_ctrl_cmd_string(Engine, CmdName, CmdArg) -> Result when Engine :: term(), CmdName :: unicode:chardata(), CmdArg :: unicode:chardata(), Result :: ok | {error, Reason :: term()}.

    Send ctrl commands to an OpenSSL engine.

    This function is the same as calling engine_ctrl_cmd_string/4 with Optional set to false.

    The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.
engine_ctrl_cmd_string(Engine, CmdName, CmdArg, Optional) -> Result when Engine :: term(), CmdName :: unicode:chardata(), CmdArg :: unicode:chardata(), Optional :: boolean(), Result :: ok | {error, Reason :: term()}.

    Send ctrl commands to an OpenSSL engine.

    Optional is a boolean argument that can relax the semantics of the function. If set to true it will only return failure if the ENGINE supported the given command name but failed while executing it, if the ENGINE does not support the command name it will simply return success without doing anything. In this case we assume the user is only supplying commands specific to the given ENGINE so we set this to false.

    The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.
engine_get_all_methods() -> Result when Result :: [engine_method_type()].

    Return a list of all possible engine methods.

    May raise exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

    See also the chapter Engine Load in the User's Guide.
engine_get_id(Engine) -> EngineId when Engine :: engine_ref(), EngineId :: unicode:chardata().

    Return the ID for the engine, or an empty binary if there is no id set.

    The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.
engine_get_name(Engine) -> EngineName when Engine :: engine_ref(), EngineName :: unicode:chardata().

    Return the name (eg a description) for the engine, or an empty binary if there is no name set.

    The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.
engine_list() -> Result when Result :: [EngineId :: unicode:chardata()].

    List the id's of all engines in OpenSSL's internal list.

    It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

    See also the chapter Engine Load in the User's Guide.

    May raise exception error:notsup in case engine functionality is not supported by the underlying OpenSSL implementation.
engine_load(EngineId, PreCmds, PostCmds) -> Result when EngineId :: unicode:chardata(), PreCmds :: [engine_cmnd()], PostCmds :: [engine_cmnd()], Result :: {ok, Engine :: engine_ref()} | {error, Reason :: term()}.

    Load an OpenSSL engine.

    Loads the OpenSSL engine given by EngineId if it is available and intialize it. Returns ok and an engine handle, or if the engine cannot be loaded an error tuple is returned.

    The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

    See also the chapter Engine Load in the User's Guide.
engine_register(Engine, EngineMethods) -> Result when Engine :: engine_ref(), EngineMethods :: [engine_method_type()], Result :: ok | {error, Reason :: term()}.

    Register engine to handle some type of methods, for example engine_method_digests.

    The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.
engine_remove(Engine) -> Result when Engine :: engine_ref(), Result :: ok | {error, Reason :: term()}.

    Remove the engine from OpenSSL's internal list.

    The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.
engine_unload(Engine) -> Result when Engine :: engine_ref(), Result :: ok | {error, Reason :: term()}.

    Unload an OpenSSL engine.

    Unloads the OpenSSL engine given by Engine. An error tuple is returned if the engine cannot be unloaded.

    The function raises a error:badarg if the parameter is in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

    See also the chapter Engine Load in the User's Guide.
engine_unregister(Engine, EngineMethods) -> Result when Engine :: engine_ref(), EngineMethods :: [engine_method_type()], Result :: ok | {error, Reason :: term()}.

    Unregister engine so it does not handle some type of methods.

    The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.
ensure_engine_loaded(EngineId, LibPath) -> Result when EngineId :: unicode:chardata(), LibPath :: unicode:chardata(), Result :: {ok, Engine :: engine_ref()} | {error, Reason :: term()}.

    Load a dynamic engine if not already done.

    Loada the engine given by EngineId and the path to the dynamic library implementing the engine. An error tuple is returned if the engine cannot be loaded.

    This function differs from the normal engine_load in the sense that it also add the engine id to OpenSSL's internal engine list. The difference between the first call and the following is that the first loads the engine with the dynamical engine and the following calls fetch it from the OpenSSL's engine list. All references that is returned are equal.

    Use engine_unload/1 function to remove the references. But remember that engine_unload/1 just removes the references to the engine and not the tag in OpenSSL's engine list. That has to be done with the engine_remove/1 function when needed (just called once, from any of the references you got).

    The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

    See also the chapter Engine Load in the User's Guide.
exor(iodata(), iodata()) -> binary().

    Perform bit-wise XOR (exclusive or) on the data supplied.

    The two byte sequences mus be of equal length.
generate_key(Type, Params, PrivKeyIn) -> {PublicKey, PrivKeyOut} when Type :: dh | ecdh | eddh | eddsa | rsa | mldsa() | mlkem512 | mlkem768 | mlkem1024 | srp | slh_dsa(), PublicKey :: dh_public() | ecdh_public() | rsa_public() | srp_public(), PrivKeyIn :: undefined | dh_private() | ecdh_private() | rsa_private() | {srp_public(), srp_private()}, PrivKeyOut :: dh_private() | ecdh_private() | rsa_private() | {srp_public(), srp_private()}, Params :: dh_params() | ecdh_params() | eddsa_params() | rsa_params() | srp_comp_params() | [].

    Generate a public key.

    See also public_key:generate_key/1.

    Uses the 3-tuple style for error handling.

    NOTE: If the linked version of cryptolib is OpenSSL 3.0

        • and the Type is dh (diffie-hellman)

        • and the parameter P (in dh_params/0) is one of the MODP groups (see RFC 3526)

        • and the optional MaxPrivateKeyBitLength parameter (in dh_params/0) is present, then the optional key length parameter must be at least 224, 256, 302, 352 and 400 for group sizes of 2048, 3072, 4096, 6144 and 8192, respectively.
hash(Type, Data) -> Digest when Type :: hash_algorithm(), Data :: iodata(), Digest :: binary().

    Compute a message digest.

    Argument Type is the digest type and argument Data is the full message.

    Uses the 3-tuple style for error handling.
hash_equals(BinA, BinB) -> Result when BinA :: binary(), BinB :: binary(), Result :: boolean().

    Compare two binaries in constant time, such as results of HMAC computations.

    Returns true if the binaries are identical, false if they are of the same length but not identical. The function raises an error:badarg exception if the binaries are of different size.
hash_final(State) -> Digest when State :: hash_state(), Digest :: binary().

    Finalize a streaming hash calculation.

    Argument State as returned from the last call to hash_update. The size of Digest is determined by the type of hash function used to generate it.

    Uses the 3-tuple style for error handling.
hash_info(Type) -> Result when Type :: hash_algorithm(), Result :: #{size := integer(), block_size := integer(), type := integer()}.

    Get information about a hash algorithm.

    Returns a map with information about block_size, size and possibly other properties of the hash algorithm in question.

    For a list of supported hash algorithms, see supports(hashs).
hash_init(Type) -> State when Type :: hash_algorithm(), State :: hash_state().

    Initialize the state for a streaming hash digest calculation.

    Argument Type determines which digest to use. The returned state should be used as argument to hash_update/2.

    Uses the 3-tuple style for error handling.
hash_update(State, Data) -> NewState when State :: hash_state(), NewState :: hash_state(), Data :: iodata().

    Add data to a streaming digest calculation.

    Update the digest using the given Data of any length.

    Argument State must have been generated by hash_init or a previous call to this function.

    Returns NewState that must be passed into the next call to hash_update/2 or hash_final/1.

    Uses the 3-tuple style for error handling.
hash_xof(Type, Data, Length) -> Digest when Type :: hash_xof_algorithm(), Data :: iodata(), Length :: non_neg_integer(), Digest :: binary().

    Compute a message digest for an xof_algorithm.

    Argument Type is the type of digest, Data is the full text and Length is the digest length in bits.

    Uses the 3-tuple style for error handling.

    May raise exception error:notsup in case the chosen Type is not supported by the underlying libcrypto implementation.
info() -> #{compile_type := normal | debug | valgrind | asan, cryptolib_version_compiled := string() | undefined, cryptolib_version_linked := string(), link_type := dynamic | static, otp_crypto_version := string(), fips_provider_available => boolean(), fips_provider_buildinfo => string()}.

    Get information about crypto and the OpenSSL backend.

    Returns a map with information about the compilation and linking of crypto.

    Example:

        1> crypto:info().
        #{compile_type => normal,
          cryptolib_version_compiled => "OpenSSL 3.0.0 7 sep 2021",
          cryptolib_version_linked => "OpenSSL 3.0.0 7 sep 2021",
          link_type => dynamic,
          otp_crypto_version => "5.0.2",
          fips_provider_available => true,
          fips_provider_buildinfo => "3.0.0"}
        2>

    More association types than documented may be present in the map. Some of the associations (like fips) may be absent if not supported.
info_fips() -> not_supported | not_enabled | enabled.

    Get information about the operating status of FIPS.

    Returns the FIPS operating status of crypto and the underlying libcrypto library. If crypto was built with FIPS support this can be either enabled (when running in FIPS mode) or not_enabled. For other builds this value is always not_supported.

    See configuration parameter fips_mode about how to enable FIPS mode.

    WARNING: In FIPS mode all non-FIPS compliant algorithms are disabled and raise exception error:notsup. Check supports(ciphers) that in FIPS mode returns the restricted list of available algorithms.
info_lib() -> [{Name, VerNum, VerStr}] when Name :: binary(), VerNum :: integer(), VerStr :: binary().

    Get the name and version of the libraries used by crypto.

    Name is the name of the library. VerNum is the numeric version according to the library's own versioning scheme. VerStr contains a text variant of the version.

        > info_lib().
        [{<<"OpenSSL">>,269484095,<<"OpenSSL 1.1.0c  10 Nov 2016"">>}]

    NOTE: From OTP R16 the numeric version represents the version of the OpenSSL header files (openssl/opensslv.h) used when crypto was compiled. The text variant represents the libcrypto library used at runtime. In earlier OTP versions both numeric and text was taken from the library.
mac(Type :: poly1305, Key, Data) -> Mac when Key :: iodata(), Data :: iodata(), Mac :: binary().

    Compute a poly1305 MAC (Message Authentication Code).

    Same as mac(Type, undefined, Key, Data).

    Uses the 3-tuple style for error handling.
mac(Type, SubType, Key, Data) -> Mac when Type :: hmac | cmac | poly1305, SubType :: hmac_hash_algorithm() | cmac_cipher_algorithm() | undefined, Key :: iodata(), Data :: iodata(), Mac :: binary().

    Compute a MAC (Message Authentication Code).

    Argument Type is the type of MAC and Data is the full message.

    SubType depends on the MAC Type:

        • For hmac it is a hash algorithm, see Algorithm Details in the User's Guide.

        • For cmac it is a cipher suitable for cmac, see Algorithm Details in the User's Guide.

        • For poly1305 it should be set to undefined or the mac/2 function could be used instead, see Algorithm Details in the User's Guide.

    Key is the authentication key with a length according to the Type and SubType. The key length could be found with the hash_info/1 (hmac) for and cipher_info/1 (cmac) functions. For poly1305 the key length is 32 bytes. Note that the cryptographic quality of the key is not checked.

    The Mac result will have a default length depending on the Type and SubType. To set a shorter length, use macN/4 or macN/5 instead. The default length is documented in Algorithm Details in the User's Guide.

    Uses the 3-tuple style for error handling.
macN(Type :: poly1305, Key, Data, MacLength) -> Mac when Key :: iodata(), Data :: iodata(), Mac :: binary(), MacLength :: pos_integer().

    Compute a poly1305 MAC (Message Authentication Code) with a limited length.

    Same as macN(Type, undefined, Key, Data, MacLength).

    Uses the 3-tuple style for error handling.
macN(Type, SubType, Key, Data, MacLength) -> Mac when Type :: hmac | cmac | poly1305, SubType :: hmac_hash_algorithm() | cmac_cipher_algorithm() | undefined, Key :: iodata(), Data :: iodata(), Mac :: binary(), MacLength :: pos_integer().

    Compute a MAC (Message Authentication Code) with a limited length.

    Works like mac/3 and mac/4 but MacLength will limit the size of the resultant Mac to at most MacLength bytes. Note that if MacLength is greater than the actual number of bytes returned from the underlying hash, the returned hash will have that shorter length instead.

    The max MacLength is documented in Algorithm Details in the User's Guide.
mac_final(State) -> Mac when State :: mac_state(), Mac :: binary().

    Finalize a streaming MAC operation.

    Argument State is the state as returned by the last call to mac_update/2.

    The Mac result will have a default length depending on the Type and SubType in the mac_init/2,3 call. To set a shorter length, use mac_finalN/2 instead. The default length is documented in Algorithm Details in the User's Guide.

    Uses the 3-tuple style for error handling.
mac_finalN(State, MacLength) -> Mac when State :: mac_state(), MacLength :: pos_integer(), Mac :: binary().

    Finalize a MAC operation with a custom length.

    Argument State is the state as returned by the last call to mac_update/2.

    Mac will be a binary with at most MacLength bytes. Note that if MacLength is greater than the actual number of bytes returned from the underlying hash, the returned hash will have that shorter length instead.

    The max MacLength is documented in Algorithm Details in the User's Guide.

    Uses the 3-tuple style for error handling.
mac_init(Type :: poly1305, Key) -> State when Key :: iodata(), State :: mac_state().

    Initialize a state for streaming poly1305 MAC calculation.

    Same as mac_init(Type, undefined, Key).

    Uses the 3-tuple style for error handling.
mac_init(Type, SubType, Key) -> State when Type :: hmac | cmac | poly1305, SubType :: hmac_hash_algorithm() | cmac_cipher_algorithm() | undefined, Key :: iodata(), State :: mac_state().

    Initialize the state for streaming MAC calculation.

    Type determines which mac algorithm to use in the MAC operation.

    SubType depends on the MAC Type:

        • For hmac it is a hash algorithm, see Algorithm Details in the User's Guide.

        • For cmac it is a cipher suitable for cmac, see Algorithm Details in the User's Guide.

        • For poly1305 it should be set to undefined or the mac/2 function could be used instead, see Algorithm Details in the User's Guide.

    Key is the authentication key with a length according to the Type and SubType. The key length could be found with the hash_info/1 (hmac) for and cipher_info/1 (cmac) functions. For poly1305 the key length is 32 bytes. Note that the cryptographic quality of the key is not checked.

    The returned State should be used in one or more subsequent calls to mac_update/2. The MAC value is finally returned by calling mac_final/1 or mac_finalN/2.

    Uses the 3-tuple style for error handling.

    See examples in the User's Guide.
mac_update(State0, Data) -> State when Data :: iodata(), State0 :: mac_state(), State :: mac_state().

    Add data to a streaming MAC calculation.

    Update the MAC represented by State0 using the given Data which could be of any length.

    The State0 is the State value originally from a MAC init function, that is mac_init/2, mac_init/3 or the last call to mac_update/2. The value State0 is returned unchanged by the function as a reference to a mutated internal state. Hence, it is not possible to branch off a data stream by reusing old states.

    Uses the 3-tuple style for error handling.
mod_pow(N, P, M) -> Result when N :: binary() | integer(), P :: binary() | integer(), M :: binary() | integer(), Result :: binary() | error.

    Compute the function N^P mod M.
pbkdf2_hmac(Digest, Pass, Salt, Iter, KeyLen) -> Result when Digest :: sha | sha224 | sha256 | sha384 | sha512 | sha512_224 | sha512_256, Pass :: binary(), Salt :: binary(), Iter :: pos_integer(), KeyLen :: pos_integer(), Result :: binary().

    PKCS #5 PBKDF2 (Password-Based Key Derivation Function 2) in combination with HMAC.

    Uses the 3-tuple style for error handling.
private_decrypt(Algorithm, CipherText, PrivateKey, Options) -> PlainText when Algorithm :: pk_encrypt_decrypt_algs(), CipherText :: binary(), PrivateKey :: rsa_private() | engine_key_ref(), Options :: pk_encrypt_decrypt_opts(), PlainText :: binary().

    Decrypt using a private key.

    Decrypts the CipherText, encrypted with public_encrypt/4 (or equivalent function) using the PrivateKey, and returns the plaintext (message digest). This is a low level signature verification operation used for instance by older versions of the SSL protocol. See also public_key:decrypt_private/2,3

    Uses the 3-tuple style for error handling.

    WARNING: This is a legacy function, for security reasons do not use with rsa_pkcs1_padding.
private_encrypt(Algorithm, PlainText, PrivateKey, Options) -> CipherText when Algorithm :: pk_encrypt_decrypt_algs(), PlainText :: binary(), PrivateKey :: rsa_private() | engine_key_ref(), Options :: pk_encrypt_decrypt_opts(), CipherText :: binary().

    Encrypt using a private key.

    Encrypts the PlainText using the PrivateKey and returns the ciphertext. This is a low level signature operation used for instance by older versions of the SSL protocol. See also public_key:encrypt_private/2,3

    Uses the 3-tuple style for error handling.

    Public-key decryption using the private key. See also crypto:private_decrypt/4

    WARNING: This is a legacy function, for security reasons do not use with rsa_pkcs1_padding. For digital signatures use of sign/4 together with verify/5 is the prefered solution.
privkey_to_pubkey(Type, EnginePrivateKeyRef) -> PublicKey when Type :: rsa | dss, EnginePrivateKeyRef :: engine_key_ref(), PublicKey :: rsa_public() | dss_public().

    Fetch public key from a private key stored in an Engine.

    The key must be of the type indicated by the Type parameter.
public_decrypt(Algorithm, CipherText, PublicKey, Options) -> PlainText when Algorithm :: pk_encrypt_decrypt_algs(), CipherText :: binary(), PublicKey :: rsa_public() | engine_key_ref(), Options :: pk_encrypt_decrypt_opts(), PlainText :: binary().

    Decrypt using a public key.

    Decrypts the CipherText, encrypted with private_encrypt/4(or equivalent function) using the PublicKey, and returns the plaintext (message digest). This is a low level signature verification operation used for instance by older versions of the SSL protocol. See also public_key:decrypt_public/2,3

    Uses the 3-tuple style for error handling.

    WARNING: This is a legacy function, for security reasons do not use with rsa_pkcs1_padding. For digital signatures use of verify/5 together with sign/4 is the prefered solution.
public_encrypt(Algorithm, PlainText, PublicKey, Options) -> CipherText when Algorithm :: pk_encrypt_decrypt_algs(), PlainText :: binary(), PublicKey :: rsa_public() | engine_key_ref(), Options :: pk_encrypt_decrypt_opts(), CipherText :: binary().

    Encrypt using a public key.

    Encrypts the PlainText (message digest) using the PublicKey and returns the CipherText. This is a low level signature operation used for instance by older versions of the SSL protocol. See also public_key:encrypt_public/2,3

    Uses the 3-tuple style for error handling.

    WARNING: This is a legacy function, for security reasons do not use together with rsa_pkcs1_padding.
rand_seed() -> rand:state().

    Create a generator for rand and save it in the process dictionary.

    Equivalent to rand_seed_s/0 but also saves the returned state object (generator) in the process dictionary. That is, it is equivalent to rand:seed(rand_seed_s()).

    See rand:seed/1 and rand_seed_s/0.

    Example

        _ = crypto:rand_seed(),
        IntegerValue = rand:uniform(42), % 1 .. 42
        FloatValue = rand:uniform().     % [0.0; 1.0)

        Note

        Note that when using the process dictionary for cryptographically secure random numbers one has to ensure that no code called between initializing the generator and between generating numbers accidentally alters the generator state in the process dictionary. The safe approach is to use the rand functions that do not use the process dictionary but take an explicit state argument: the ones suffixed _s. Thereby it is rather rand_seed_s/0 that should be used instead of this function.
rand_seed(binary()) -> ok.

    Mixes in the bytes of the given binary into the internal state of OpenSSL's random number generator.

    This calls the RAND_seed function from OpenSSL. Only use this if the system you are running on does not have enough "randomness" built in. Normally this is when strong_rand_bytes/1 or a generator from rand_seed_alg_s/1 raises error:low_entropy.
rand_seed_alg(Alg :: crypto | crypto_cache) -> {rand:alg_handler(), atom() | rand_cache_seed()}.

    Create a generator for rand with specified algorithm, and save it in the process dictionary.

    Equivalent rand_seed_alg_s/1 but also saves the returned state object (generator) in the process dictionary. That is, it is equivalent to rand:seed(rand_seed_alg_s(Alg)).

    See rand:seed/1 and rand_seed_alg_s/1. Note the warning about the usage of the process dictionary in rand_seed/0.

    Example

        _ = crypto:rand_seed_alg(crypto_cache),
        IntegerValue = rand:uniform(42), % 1 .. 42
        FloatValue = rand:uniform().     % [0.0; 1.0)
rand_seed_alg(Alg :: crypto_aes, Seed :: term()) -> {rand:alg_handler(), atom() | rand_cache_seed()}.

    Create and seed a generator for rand with specified algorithm, and save it in the process dictionary.

    Equivalent to rand_seed_alg_s/2 but also saves the returned state object (generator) in the process dictionary. That is, it is equivalent to rand:seed(rand_seed_alg_s(Alg, Seed)).

    See rand:seed/1 and rand_seed_alg_s/2. Note the warning about the usage of the process dictionary in rand_seed/0.

    Example

        _ = crypto:rand_seed_alg(crypto_aes, "my seed"),
        IntegerValue = rand:uniform(42), % 1 .. 42
        FloatValue = rand:uniform(),     % [0.0; 1.0)
        _ = crypto:rand_seed_alg(crypto_aes, "my seed"),
        IntegerValue = rand:uniform(42), % Same values
        FloatValue = rand:uniform().     % again
rand_seed_alg_s(Alg :: crypto | crypto_cache) -> {rand:alg_handler(), atom() | rand_cache_seed()}.

    Create a generator for rand with specified algorithm.

    Create a state object (generator) for random number generation, which when used by the rand functions produce cryptographically strong random number.

    See also rand:seed_s/1 and for example rand:uniform_s/2.

    If Alg is crypto this function is equivalent to rand_seed_s/0.

    If Alg is crypto_cache the returned generator fetches random data with OpenSSL's RAND_bytes and caches it as 56 bit numbers which makes calculations fast on 64 bit machines.

    Example

        S0 = crypto:rand_seed_alg_s(crypto_cache),
        {IntegerValue, S1} = rand:uniform(42, S0), % 1 .. 42
        {FloatValue, S2} = rand:uniform(S1).       % [0.0; 1.0)

    May cause the rand functions using this state object to raise the exception error:low_entropy in case the random generator failed due to lack of secure "randomness".

    The cache size can be changed from its default value using the crypto app's configuration parameter rand_cache_size.

    NOTE: The state returned from this function cannot be used to get a reproducible random sequence as from the other rand functions, since that would not be cryptographically safe. In fact when random data is cached some numbers may get reproduced occasionally, but this is unpredictable. The only supported usage is to generate one distinct random sequence.
rand_seed_alg_s(Alg :: crypto_aes, Seed :: term()) -> {rand:alg_handler(), atom() | rand_cache_seed()}.

    Create and seed a generator for rand with specified algorithm.

    Create a state object (generator) for random number generation, which when used by the rand functions produce cryptographically unpredictable random numbers

    See also rand:seed_s/1, and for example rand:uniform_s/2. Compare to rand_seed_alg/1.

    To get a long period the Xoroshiro928 generator from the rand module is used as a counter (with period 2^928 - 1) and the generator states are scrambled through AES to create 58-bit pseudo random values.

    The result should be statistically completely unpredictable random values, since the scrambling is cryptographically strong and the period is ridiculously long. But the generated numbers are not to be regarded as cryptographically strong since there is no re-keying schedule, and since the sequence is repeated for the same seed.

        • If you need cryptographically strong random numbers use rand_seed_alg_s/1 with Alg =:= crypto or Alg =:= crypto_cache.

        • If you need to be able to repeat the sequence use this function with Alg =:= crypto_aes.

        • If you do not need the statistical quality of this function, there are faster algorithms in the rand module.

    Example

        S0 = crypto:rand_seed_alg_s(crypto_aes, "my seed"),
        {IntegerValue, S1} = rand:uniform(42, S0), % 1 .. 42
        {FloatValue, S2 = rand:uniform(S1),        % [0.0; 1.0)
        S3 = crypto:rand_seed_alg_s(crypto_aes, "my seed"),
        {IntegerValue, S4} = rand:uniform(42, S3), % Same values
        {FloatValue, S5} = rand:uniform(S4).       % again

    Thanks to the used generator the state object supports the rand:jump/0,1 function with distance 2^512.

    Numbers are generated in batches and cached for speed reasons. The cache size can be changed from its default value using the crypto app's configuration parameter rand_cache_size.
rand_seed_s() -> rand:state().

    Create a generator for rand.

    Create a state object (generator) for random number generation, which when used by the rand functions produce cryptographically strong random numbers (based on OpenSSL's BN_rand_range function). See also rand:seed_s/1, and for example rand:uniform_s/2.

    Example

        S0 = crypto:rand_seed_s(),
        {RandomInteger, S1} = rand:uniform_s(1000, S0).

    May cause the rand functions using this state object to raise the exception error:low_entropy in case the random generator failed due to lack of secure "randomness".

    NOTE: The state returned from this function cannot be used to get a reproducible random sequence as from the other rand functions, since that would not be cryptographically safe. The only supported usage is to generate one distinct random sequence.
rand_uniform(crypto_integer(), crypto_integer()) -> crypto_integer().

    Deprecated: crypto:rand_uniform/2 is deprecated; use strong_rand_range/1 instead

    Generate a random integer number.

    The interval is From =< N < To. Uses the crypto library pseudo-random number generator. To must be larger than From.

    NOTE: This function is deprecated because it originally used the OpenSSL method BN_pseudo_rand_range that was not cryptographically strong and could not run out of entropy. That behaviour changed in OpenSSL and this function cannot be fixed without making it raise error:low_entropy, which is not backwards compatible. Instead, use strong_rand_range(To - From) + From Be aware of the possible error:low_entropy exception.
sign(Algorithm, DigestType, Msg, Key, Options) -> Signature when Algorithm :: pk_sign_verify_algs(), DigestType :: rsa_digest_type() | dss_digest_type() | ecdsa_digest_type() | none, Msg :: iodata() | {digest, iodata()}, Key :: rsa_private() | dss_private() | [ecdsa_private() | ecdsa_params()] | [eddsa_private() | eddsa_params()] | mldsa_private() | slh_dsa_private() | engine_key_ref(), Options :: pk_sign_verify_opts(), Signature :: binary().

    Create a digital signature.

    The msg is either the binary "cleartext" data to be signed or it is the hashed value of "cleartext" i.e. the digest (plaintext).

    Algorithm dss can only be used together with digest type sha.

    Uses the 3-tuple style for error handling.

    See also public_key:sign/3.
start() -> ok | {error, Reason :: term()}.

    Deprecated: crypto:start/0 is deprecated; use application:start(crypto) instead

    Use application:start(crypto) instead.

    WARNING: This function does not work if FIPS mode is to be enabled. FIPS mode will be disabled even if configuration parameter fips_mode is set to true. Use application:start(crypto) instead.
stop() -> ok | {error, Reason :: term()}.

    Deprecated: crypto:stop/0 is deprecated; use application:stop(crypto) instead

    Use application:stop(crypto) instead.
strong_rand_bytes(N :: non_neg_integer()) -> binary().

    Generate bytes with randomly uniform values 0..255.

    Returns the result in a binary with N bytes.

    Uses a cryptographically secure PRNG seeded and periodically mixed with operating system provided entropy. By default this is the RAND_bytes method from OpenSSL.

    May raise exception error:low_entropy in case the random generator failed due to lack of secure "randomness".
strong_rand_range(Range :: pos_integer()) -> N :: non_neg_integer(); (Range :: binary()) -> N :: binary().

    Generate a random integer in a specified range.

    The returned random integer is in the interval is 0 =< N < Range.

    Uses the crypto library random number generator BN_rand_range.

    If the Range argument is a pos_integer/0 the return value is a non_neg_integer/0. If the Range argument is a positive integer in a binary/0, the return value is a non-negative integer in a binary/0.

    May raise exception error:low_entropy in case the random generator failed due to lack of secure "randomness".
supports(Type) -> Support when Type :: hashs | ciphers | kems | public_keys | macs | curves | rsa_opts, Support :: Hashs | Ciphers | KEMs | PKs | Macs | Curves | RSAopts, Hashs :: [sha1() | sha2() | sha3() | sha3_xof() | blake2() | ripemd160 | compatibility_only_hash()], Ciphers :: [cipher()], KEMs :: [kem()], PKs :: [rsa | dss | ecdsa | dh | ecdh | eddh | ec_gf2m], Macs :: [hmac | cmac | poly1305], Curves :: [ec_named_curve() | edwards_curve_dh() | edwards_curve_ed()], RSAopts :: [rsa_sign_verify_opt() | rsa_opt()].

    Get which crypto algorithms that are supported by the underlying libcrypto library.

    See hash_info/1 and cipher_info/1 for information about the hash and cipher algorithms.
verify(Algorithm, DigestType, Msg, Signature, Key, Options) -> Result when Algorithm :: pk_sign_verify_algs(), DigestType :: rsa_digest_type() | dss_digest_type() | ecdsa_digest_type() | none, Msg :: iodata() | {digest, iodata()}, Signature :: binary(), Key :: rsa_public() | dss_public() | [ecdsa_public() | ecdsa_params()] | [eddsa_public() | eddsa_params()] | mldsa_public() | slh_dsa_public() | engine_key_ref(), Options :: pk_sign_verify_opts(), Result :: boolean().

    Verify a digital signature.

    The msg is either the binary "cleartext" data to be signed or it is the hashed value of "cleartext" i.e. the digest (plaintext).

    Algorithm dss can only be used together with digest type sha.

    Uses the 3-tuple style for error handling.

    See also public_key:verify/4.