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.tr \(*W- . ds -- \(*W- . ds PI pi . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch . if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch . ds L" "" . ds R" "" . ds C` "" . ds C' "" 'br\} . ds -- \|\(em\| . ds PI \(*p . ds L" `` . ds R" '' . ds C` . ds C' 'br\}
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.. .nr rF 0 . if \nF \{\ . de IX . tm Index:\\$1\t\\n%\t"\\$2" .. . if !\nF==2 \{\ . nr % 0 . nr F 2 . \} . \} .\} .rr rF Fear. Run. Save yourself. No user-serviceable parts.
. \" fudge factors for nroff and troff . ds #H 0 . ds #V .8m . ds #F .3m . ds #[ \f1 . ds #] .\} . ds #H ((1u-(\\\\n(.fu%2u))*.13m) . ds #V .6m . ds #F 0 . ds #[ \& . ds #] \& .\} . \" simple accents for nroff and troff . ds ' \& . ds ` \& . ds ^ \& . ds , \& . ds ~ ~ . ds / .\} . ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u" . ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u' . ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u' . ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u' . ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u' . ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u' .\} . \" troff and (daisy-wheel) nroff accents . \" corrections for vroff . \" for low resolution devices (crt and lpr) \{\ . ds : e . ds 8 ss . ds o a . ds d- d\h'-1'\(ga . ds D- D\h'-1'\(hy . ds th \o'bp' . ds Th \o'LP' . ds ae ae . ds Ae AE .\} ========================================================================
Title "EVP_KDF-TLS13_KDF 7ossl"
way too many mistakes in technical documents.
The \s-1EVP_KDF-TLS13_KDF\s0 algorithm implements the \s-1HKDF\s0 key derivation function as used by \s-1TLS 1.3.\s0
0 Item "digest (OSSL_KDF_PARAM_DIGEST) <UTF8 string>" Item "key (OSSL_KDF_PARAM_KEY) <octet string>" Item "salt (OSSL_KDF_PARAM_SALT) <octet string>"
These parameters work as described in \*(L"\s-1PARAMETERS\*(R"\s0 in \s-1EVP_KDF\s0\|(3). Item "prefix (OSSL_KDF_PARAM_PREFIX) <octet string>" This parameter sets the label prefix on the specified \s-1TLS 1.3 KDF\s0 context. For \s-1TLS 1.3\s0 this should be set to the \s-1ASCII\s0 string \*(L"tls13 \*(R" without a trailing zero byte. Refer to \s-1RFC 8446\s0 section 7.1 \*(L"Key Schedule\*(R" for details. Item "label (OSSL_KDF_PARAM_LABEL) <octet string>" This parameter sets the label on the specified \s-1TLS 1.3 KDF\s0 context. Refer to \s-1RFC 8446\s0 section 7.1 \*(L"Key Schedule\*(R" for details. Item "data (OSSL_KDF_PARAM_DATA) <octet string>" This parameter sets the context data on the specified \s-1TLS 1.3 KDF\s0 context. Refer to \s-1RFC 8446\s0 section 7.1 \*(L"Key Schedule\*(R" for details. Item "mode (OSSL_KDF_PARAM_MODE) <UTF8 string> or <integer>" This parameter sets the mode for the \s-1TLS 1.3 KDF\s0 operation. There are two modes that are currently defined:
Item "EXTRACT_ONLY or EVP_KDF_HKDF_MODE_EXTRACT_ONLY" In this mode calling EVP_KDF_derive\|(3) will just perform the extract operation. The value returned will be the intermediate fixed-length pseudorandom key K. The keylen parameter must match the size of K, which can be looked up by calling EVP_KDF_CTX_get_kdf_size() after setting the mode and digest. .Sp The digest, key and salt values must be set before a key is derived otherwise an error will occur. Item "EXPAND_ONLY or EVP_KDF_HKDF_MODE_EXPAND_ONLY" In this mode calling EVP_KDF_derive\|(3) will just perform the expand operation. The input key should be set to the intermediate fixed-length pseudorandom key K returned from a previous extract operation. .Sp The digest, key and info values must be set before a key is derived otherwise an error will occur.
The \s-1OSSL_PARAM\s0 array passed to EVP_KDF_derive\|(3) or \fBEVP_KDF_CTX_set_params\|(3) must specify all of the parameters required. This \s-1KDF\s0 does not support a piecemeal approach to providing these.
A context for a \s-1TLS 1.3 KDF\s0 can be obtained by calling:
.Vb 2 EVP_KDF *kdf = EVP_KDF_fetch(NULL, "TLS13-KDF", NULL); EVP_KDF_CTX *kctx = EVP_KDF_CTX_new(kdf); .Ve
The output length of a \s-1TLS 1.3 KDF\s0 expand operation is specified via the \fIkeylen parameter to the EVP_KDF_derive\|(3) function. When using \s-1EVP_KDF_HKDF_MODE_EXTRACT_ONLY\s0 the keylen parameter must equal the size of the intermediate fixed-length pseudorandom key otherwise an error will occur. For that mode, the fixed output size can be looked up by calling \fBEVP_KDF_CTX_get_kdf_size() after setting the mode and digest on the \fB\s-1EVP_KDF_CTX\s0.
Licensed under the Apache License 2.0 (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.