{ "content": [ { "type": "text", "text": "# OPENSSL-KDF (man)\n\n## NAME\n\nopenssl-kdf - perform Key Derivation Function operations\n\n## SYNOPSIS\n\nopenssl kdf [-help] [-cipher] [-digest] [-mac] [-kdfopt nm:v] [-keylen num] [-out filename]\n[-binary] [-provider name] [-provider-path path] [-propquery propq] kdfname\n\n## DESCRIPTION\n\nThe key derivation functions generate a derived key from either a secret or password.\n\n## Sections\n\n- **NAME**\n- **SYNOPSIS**\n- **DESCRIPTION**\n- **OPTIONS** (11 subsections)\n- **EXAMPLES**\n- **NOTES**\n- **SEE ALSO**\n- **HISTORY**\n- **COPYRIGHT**\n\nUse structuredContent.sections for detailed options, examples, and full documentation.\n" } ], "structuredContent": { "command": "OPENSSL-KDF", "section": "", "mode": "man", "summary": "openssl-kdf - perform Key Derivation Function operations", "synopsis": "openssl kdf [-help] [-cipher] [-digest] [-mac] [-kdfopt nm:v] [-keylen num] [-out filename]\n[-binary] [-provider name] [-provider-path path] [-propquery propq] kdfname", "tldr_summary": null, "tldr_examples": [], "tldr_source": null, "flags": [ { "flag": "", "long": null, "arg": null, "description": "Print a usage message." }, { "flag": "", "long": null, "arg": null, "description": "The output size of the derived key. This field is required." }, { "flag": "", "long": null, "arg": null, "description": "Filename to output to, or standard output by default." }, { "flag": "", "long": null, "arg": null, "description": "Output the derived key in binary form. Uses hexadecimal text format if not specified." }, { "flag": "", "long": null, "arg": null, "description": "Specify the cipher to be used by the KDF. Not all KDFs require a cipher and it is an error to use this option in such cases." }, { "flag": "", "long": null, "arg": null, "description": "Specify the digest to be used by the KDF. Not all KDFs require a digest and it is an error to use this option in such cases. To see the list of supported digests, use \"openssl list -digest-commands\"." }, { "flag": "", "long": null, "arg": null, "description": "Specify the MAC to be used by the KDF. Not all KDFs require a MAC and it is an error to use this option in such cases." }, { "flag": "", "long": null, "arg": null, "description": "Passes options to the KDF algorithm. A comprehensive list of parameters can be found in \"PARAMETERS\" in EVPKDF(3). Common parameter names used by EVPKDFCTXsetparams() are: key:string Specifies the secret key as an alphanumeric string (use if the key contains printable characters only). The string length must conform to any restrictions of the KDF algorithm. A key must be specified for most KDF algorithms. hexkey:string Alternative to the key: option where the secret key is specified in hexadecimal form (two hex digits per byte). pass:string Specifies the password as an alphanumeric string (use if the password contains printable characters only). The password must be specified for PBKDF2 and scrypt. hexpass:string Alternative to the pass: option where the password is specified in hexadecimal form (two hex digits per byte). salt:string Specifies a non-secret unique cryptographic salt as an alphanumeric string (use if it contains printable characters only). The length must conform to any restrictions of the KDF algorithm. A salt parameter is required for several KDF algorithms, such as EVPKDF-PBKDF2(7). hexsalt:string Alternative to the salt: option where the salt is specified in hexadecimal form (two hex digits per byte). info:string Some KDF implementations, such as EVPKDF-HKDF(7), take an 'info' parameter for binding the derived key material to application- and context-specific information. Specifies the info, fixed info, other info or shared info argument as an alphanumeric string (use if it contains printable characters only). The length must conform to any restrictions of the KDF algorithm. hexinfo:string Alternative to the info: option where the info is specified in hexadecimal form (two hex digits per byte). digest:string This option is identical to the -digest option. cipher:string This option is identical to the -cipher option. mac:string This option is identical to the -mac option." }, { "flag": "", "long": null, "arg": null, "description": "" }, { "flag": "", "long": null, "arg": null, "description": "" }, { "flag": "", "long": null, "arg": null, "description": "See \"Provider Options\" in openssl(1), provider(7), and property(7). kdfname Specifies the name of a supported KDF algorithm which will be used. The supported algorithms names include TLS1-PRF, HKDF, SSKDF, PBKDF2, SSHKDF, X942KDF-ASN1, X942KDF-CONCAT, X963KDF and SCRYPT." } ], "examples": [ "Use TLS1-PRF to create a hex-encoded derived key from a secret key and seed:", "openssl kdf -keylen 16 -kdfopt digest:SHA2-256 -kdfopt key:secret \\", "-kdfopt seed:seed TLS1-PRF", "Use HKDF to create a hex-encoded derived key from a secret key, salt and info:", "openssl kdf -keylen 10 -kdfopt digest:SHA2-256 -kdfopt key:secret \\", "-kdfopt salt:salt -kdfopt info:label HKDF", "Use SSKDF with KMAC to create a hex-encoded derived key from a secret key, salt and info:", "openssl kdf -keylen 64 -kdfopt mac:KMAC-128 -kdfopt maclen:20 \\", "-kdfopt hexkey:b74a149a161545 -kdfopt hexinfo:348a37a2 \\", "-kdfopt hexsalt:3638271ccd68a2 SSKDF", "Use SSKDF with HMAC to create a hex-encoded derived key from a secret key, salt and info:", "openssl kdf -keylen 16 -kdfopt mac:HMAC -kdfopt digest:SHA2-256 \\", "-kdfopt hexkey:b74a149a -kdfopt hexinfo:348a37a2 \\", "-kdfopt hexsalt:3638271c SSKDF", "Use SSKDF with Hash to create a hex-encoded derived key from a secret key, salt and info:", "openssl kdf -keylen 14 -kdfopt digest:SHA2-256 \\", "-kdfopt hexkey:6dbdc23f045488 \\", "-kdfopt hexinfo:a1b2c3d4 SSKDF", "Use SSHKDF to create a hex-encoded derived key from a secret key, hash and sessionid:", "openssl kdf -keylen 16 -kdfopt digest:SHA2-256 \\", "-kdfopt hexkey:0102030405 \\", "-kdfopt hexxcghash:06090A \\", "-kdfopt hexsessionid:01020304 \\", "-kdfopt type:A SSHKDF", "Use PBKDF2 to create a hex-encoded derived key from a password and salt:", "openssl kdf -keylen 32 -kdfopt digest:SHA256 -kdfopt pass:password \\", "-kdfopt salt:salt -kdfopt iter:2 PBKDF2", "Use scrypt to create a hex-encoded derived key from a password and salt:", "openssl kdf -keylen 64 -kdfopt pass:password -kdfopt salt:NaCl \\", "-kdfopt n:1024 -kdfopt r:8 -kdfopt p:16 \\", "-kdfopt maxmembytes:10485760 SCRYPT" ], "see_also": [ { "name": "openssl", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/openssl/1/json" }, { "name": "openssl-pkeyutl", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/openssl-pkeyutl/1/json" }, { "name": "EVPKDF", "section": "3", "url": "https://www.chedong.com/phpMan.php/man/EVPKDF/3/json" }, { "name": "EVPKDF-SCRYPT", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/EVPKDF-SCRYPT/7/json" }, { "name": "EVPKDF-TLS1PRF", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/EVPKDF-TLS1PRF/7/json" }, { "name": "EVPKDF-PBKDF2", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/EVPKDF-PBKDF2/7/json" }, { "name": "EVPKDF-HKDF", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/EVPKDF-HKDF/7/json" }, { "name": "EVPKDF-SS", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/EVPKDF-SS/7/json" }, { "name": "EVPKDF-SSHKDF", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/EVPKDF-SSHKDF/7/json" }, { "name": "EVPKDF-X942-ASN1", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/EVPKDF-X942-ASN1/7/json" }, { "name": "EVPKDF-X942-CONCAT", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/EVPKDF-X942-CONCAT/7/json" }, { "name": "EVPKDF-X963", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/EVPKDF-X963/7/json" } ], "section_outline": [ { "name": "NAME", "lines": 2, "subsections": [] }, { "name": "SYNOPSIS", "lines": 3, "subsections": [] }, { "name": "DESCRIPTION", "lines": 2, "subsections": [] }, { "name": "OPTIONS", "lines": 1, "subsections": [ { "name": "-help", "lines": 2 }, { "name": "-keylen _", "lines": 2 }, { "name": "-out _", "lines": 2 }, { "name": "-binary", "lines": 2 }, { "name": "-cipher _", "lines": 3 }, { "name": "-digest _", "lines": 4 }, { "name": "-mac _", "lines": 3 }, { "name": "-kdfopt _", "lines": 50 }, { "name": "-provider _", "lines": 1 }, { "name": "-provider-path _", "lines": 1 }, { "name": "-propquery _", "lines": 7 } ] }, { "name": "EXAMPLES", "lines": 47, "subsections": [] }, { "name": "NOTES", "lines": 2, "subsections": [] }, { "name": "SEE ALSO", "lines": 4, "subsections": [] }, { "name": "HISTORY", "lines": 2, "subsections": [] }, { "name": "COPYRIGHT", "lines": 7, "subsections": [] } ], "sections": { "NAME": { "content": "openssl-kdf - perform Key Derivation Function operations\n", "subsections": [] }, "SYNOPSIS": { "content": "openssl kdf [-help] [-cipher] [-digest] [-mac] [-kdfopt nm:v] [-keylen num] [-out filename]\n[-binary] [-provider name] [-provider-path path] [-propquery propq] kdfname\n", "subsections": [] }, "DESCRIPTION": { "content": "The key derivation functions generate a derived key from either a secret or password.\n", "subsections": [] }, "OPTIONS": { "content": "", "subsections": [ { "name": "-help", "content": "Print a usage message.\n" }, { "name": "-keylen _", "content": "The output size of the derived key. This field is required.\n" }, { "name": "-out _", "content": "Filename to output to, or standard output by default.\n" }, { "name": "-binary", "content": "Output the derived key in binary form. Uses hexadecimal text format if not specified.\n" }, { "name": "-cipher _", "content": "Specify the cipher to be used by the KDF. Not all KDFs require a cipher and it is an\nerror to use this option in such cases.\n" }, { "name": "-digest _", "content": "Specify the digest to be used by the KDF. Not all KDFs require a digest and it is an\nerror to use this option in such cases. To see the list of supported digests, use\n\"openssl list -digest-commands\".\n" }, { "name": "-mac _", "content": "Specify the MAC to be used by the KDF. Not all KDFs require a MAC and it is an error to\nuse this option in such cases.\n" }, { "name": "-kdfopt _", "content": "Passes options to the KDF algorithm. A comprehensive list of parameters can be found in\n\"PARAMETERS\" in EVPKDF(3). Common parameter names used by EVPKDFCTXsetparams() are:\n\nkey:string\nSpecifies the secret key as an alphanumeric string (use if the key contains printable\ncharacters only). The string length must conform to any restrictions of the KDF\nalgorithm. A key must be specified for most KDF algorithms.\n\nhexkey:string\nAlternative to the key: option where the secret key is specified in hexadecimal form\n(two hex digits per byte).\n\npass:string\nSpecifies the password as an alphanumeric string (use if the password contains\nprintable characters only). The password must be specified for PBKDF2 and scrypt.\n\nhexpass:string\nAlternative to the pass: option where the password is specified in hexadecimal form\n(two hex digits per byte).\n\nsalt:string\nSpecifies a non-secret unique cryptographic salt as an alphanumeric string (use if it\ncontains printable characters only). The length must conform to any restrictions of\nthe KDF algorithm. A salt parameter is required for several KDF algorithms, such as\nEVPKDF-PBKDF2(7).\n\nhexsalt:string\nAlternative to the salt: option where the salt is specified in hexadecimal form (two\nhex digits per byte).\n\ninfo:string\nSome KDF implementations, such as EVPKDF-HKDF(7), take an 'info' parameter for\nbinding the derived key material to application- and context-specific information.\nSpecifies the info, fixed info, other info or shared info argument as an alphanumeric\nstring (use if it contains printable characters only). The length must conform to\nany restrictions of the KDF algorithm.\n\nhexinfo:string\nAlternative to the info: option where the info is specified in hexadecimal form (two\nhex digits per byte).\n\ndigest:string\nThis option is identical to the -digest option.\n\ncipher:string\nThis option is identical to the -cipher option.\n\nmac:string\nThis option is identical to the -mac option.\n" }, { "name": "-provider _", "content": "" }, { "name": "-provider-path _", "content": "" }, { "name": "-propquery _", "content": "See \"Provider Options\" in openssl(1), provider(7), and property(7).\n\nkdfname\nSpecifies the name of a supported KDF algorithm which will be used. The supported\nalgorithms names include TLS1-PRF, HKDF, SSKDF, PBKDF2, SSHKDF, X942KDF-ASN1,\nX942KDF-CONCAT, X963KDF and SCRYPT.\n" } ] }, "EXAMPLES": { "content": "Use TLS1-PRF to create a hex-encoded derived key from a secret key and seed:\n\nopenssl kdf -keylen 16 -kdfopt digest:SHA2-256 -kdfopt key:secret \\\n-kdfopt seed:seed TLS1-PRF\n\nUse HKDF to create a hex-encoded derived key from a secret key, salt and info:\n\nopenssl kdf -keylen 10 -kdfopt digest:SHA2-256 -kdfopt key:secret \\\n-kdfopt salt:salt -kdfopt info:label HKDF\n\nUse SSKDF with KMAC to create a hex-encoded derived key from a secret key, salt and info:\n\nopenssl kdf -keylen 64 -kdfopt mac:KMAC-128 -kdfopt maclen:20 \\\n-kdfopt hexkey:b74a149a161545 -kdfopt hexinfo:348a37a2 \\\n-kdfopt hexsalt:3638271ccd68a2 SSKDF\n\nUse SSKDF with HMAC to create a hex-encoded derived key from a secret key, salt and info:\n\nopenssl kdf -keylen 16 -kdfopt mac:HMAC -kdfopt digest:SHA2-256 \\\n-kdfopt hexkey:b74a149a -kdfopt hexinfo:348a37a2 \\\n-kdfopt hexsalt:3638271c SSKDF\n\nUse SSKDF with Hash to create a hex-encoded derived key from a secret key, salt and info:\n\nopenssl kdf -keylen 14 -kdfopt digest:SHA2-256 \\\n-kdfopt hexkey:6dbdc23f045488 \\\n-kdfopt hexinfo:a1b2c3d4 SSKDF\n\nUse SSHKDF to create a hex-encoded derived key from a secret key, hash and sessionid:\n\nopenssl kdf -keylen 16 -kdfopt digest:SHA2-256 \\\n-kdfopt hexkey:0102030405 \\\n-kdfopt hexxcghash:06090A \\\n-kdfopt hexsessionid:01020304 \\\n-kdfopt type:A SSHKDF\n\nUse PBKDF2 to create a hex-encoded derived key from a password and salt:\n\nopenssl kdf -keylen 32 -kdfopt digest:SHA256 -kdfopt pass:password \\\n-kdfopt salt:salt -kdfopt iter:2 PBKDF2\n\nUse scrypt to create a hex-encoded derived key from a password and salt:\n\nopenssl kdf -keylen 64 -kdfopt pass:password -kdfopt salt:NaCl \\\n-kdfopt n:1024 -kdfopt r:8 -kdfopt p:16 \\\n-kdfopt maxmembytes:10485760 SCRYPT\n", "subsections": [] }, "NOTES": { "content": "The KDF mechanisms that are available will depend on the options used when building OpenSSL.\n", "subsections": [] }, "SEE ALSO": { "content": "openssl(1), openssl-pkeyutl(1), EVPKDF(3), EVPKDF-SCRYPT(7), EVPKDF-TLS1PRF(7),\nEVPKDF-PBKDF2(7), EVPKDF-HKDF(7), EVPKDF-SS(7), EVPKDF-SSHKDF(7), EVPKDF-X942-ASN1(7),\nEVPKDF-X942-CONCAT(7), EVPKDF-X963(7)\n", "subsections": [] }, "HISTORY": { "content": "Added in OpenSSL 3.0\n", "subsections": [] }, "COPYRIGHT": { "content": "Copyright 2019-2023 The OpenSSL Project Authors. All Rights Reserved.\n\nLicensed under the Apache License 2.0 (the \"License\"). You may not use this file except in\ncompliance with the License. You can obtain a copy in the file LICENSE in the source\ndistribution or at .\n\n3.0.13 2026-07-29 OPENSSL-KDF(1SSL)", "subsections": [] } } } }