From 6942a0d6feb8d3dcbbc6a1ec6be9de7ab2df1530 Mon Sep 17 00:00:00 2001 From: Richard Levitte Date: Wed, 8 Jan 2020 11:04:15 +0100 Subject: [PATCH] DOC: New file for EVP_PKEY_size(), EVP_PKEY_bits() and EVP_PKEY_security_bits() We change the description to be about the key rather than the signature. How the key size is related to the signature is explained in the description of EVP_SignFinal() anyway. Reviewed-by: Nicola Tuveri (Merged from https://github.com/openssl/openssl/pull/10778) --- doc/man3/EVP_PKEY_size.pod | 80 ++++++++++++++++++++++++++++++++++++++ doc/man3/EVP_SignInit.pod | 24 +++--------- util/missingcrypto.txt | 1 - 3 files changed, 85 insertions(+), 20 deletions(-) create mode 100644 doc/man3/EVP_PKEY_size.pod diff --git a/doc/man3/EVP_PKEY_size.pod b/doc/man3/EVP_PKEY_size.pod new file mode 100644 index 0000000000..786c503914 --- /dev/null +++ b/doc/man3/EVP_PKEY_size.pod @@ -0,0 +1,80 @@ +=pod + +=head1 NAME + +EVP_PKEY_size, EVP_PKEY_bits, EVP_PKEY_security_bits +- EVP_PKEY information functions + +=head1 SYNOPSIS + + #include + + int EVP_PKEY_size(const EVP_PKEY *pkey); + int EVP_PKEY_bits(const EVP_PKEY *pkey); + int EVP_PKEY_security_bits(const EVP_PKEY *pkey); + +=head1 DESCRIPTION + +EVP_PKEY_size() returns the maximum suitable size for the output +buffers for almost all operations that can be done with I. +The primary documented use is with L and +L, but it isn't limited there. The returned size is +also large enough for the output buffer of L, +L, L, L. + +It must be stressed that, unless the documentation for the operation +that's being performed says otherwise, the size returned by +EVP_PKEY_size() is only preliminary and not exact, so the final +contents of the target buffer may be smaller. It is therefore crucial +to take note of the size given back by the function that performs the +operation, such as L (the I argument will +receive that length), to avoid bugs. + +EVP_PKEY_bits() returns the cryptographic length of the cryptosystem +to which the key in I belongs, in bits. Note that the definition +of cryptographic length is specific to the key cryptosystem. + +EVP_PKEY_security_bits() returns the number of security bits of the given +I, bits of security is defined in NIST SP800-57. + +=head1 RETURN VALUES + +EVP_PKEY_size(), EVP_PKEY_bits() and EVP_PKEY_security_bits() return a +positive number, or 0 if this size isn't available. + +=head1 NOTES + +Most functions that have an output buffer and are mentioned with +EVP_PKEY_size() have a functionality where you can pass NULL for the +buffer and still pass a pointer to an integer and get the exact size +that this function call delivers in the context that it's called in. +This allows those functions to be called twice, once to find out the +exact buffer size, then allocate the buffer in between, and call that +function again actually output the data. For those functions, it +isn't strictly necessary to call EVP_PKEY_size() to find out the +buffer size, but may be useful in cases where it's desirable to know +the upper limit in advance. + +It should also be especially noted that EVP_PKEY_size() shouldn't be +used to get the output size for EVP_DigestSignFinal(), according to +L. + +=head1 SEE ALSO + +L, +L, +L, +L, +L, +L + +=head1 COPYRIGHT + +Copyright 2020 The OpenSSL Project Authors. All Rights Reserved. + +Licensed under the Apache License 2.0 (the "License"). You may not use +this file except in compliance with the License. You can obtain a copy +in the file LICENSE in the source distribution or at +L. + +=cut diff --git a/doc/man3/EVP_SignInit.pod b/doc/man3/EVP_SignInit.pod index 3dad4f105a..65ef22d318 100644 --- a/doc/man3/EVP_SignInit.pod +++ b/doc/man3/EVP_SignInit.pod @@ -2,10 +2,8 @@ =head1 NAME -EVP_PKEY_size, -EVP_SignInit, EVP_SignInit_ex, EVP_SignUpdate, EVP_SignFinal, -EVP_PKEY_security_bits - EVP signing -functions +EVP_SignInit, EVP_SignInit_ex, EVP_SignUpdate, EVP_SignFinal +- EVP signing functions =head1 SYNOPSIS @@ -17,9 +15,6 @@ functions void EVP_SignInit(EVP_MD_CTX *ctx, const EVP_MD *type); - int EVP_PKEY_size(const EVP_PKEY *pkey); - int EVP_PKEY_security_bits(const EVP_PKEY *pkey); - =head1 DESCRIPTION The EVP signature routines are a high level interface to digital @@ -34,32 +29,22 @@ signature context B. This function can be called several times on the same B to include additional data. EVP_SignFinal() signs the data in B using the private key B and -places the signature in B. B must be at least EVP_PKEY_size(pkey) +places the signature in B. B must be at least C bytes in size. B is an OUT parameter, and not used as an IN parameter. The number of bytes of data written (i.e. the length of the signature) -will be written to the integer at B, at most EVP_PKEY_size(pkey) bytes +will be written to the integer at B, at most C bytes will be written. EVP_SignInit() initializes a signing context B to use the default implementation of digest B. -EVP_PKEY_size() returns the maximum size of a signature in bytes. The actual -signature returned by EVP_SignFinal() may be smaller. - -EVP_PKEY_security_bits() returns the number of security bits of the given B, -bits of security is defined in NIST SP800-57. - =head1 RETURN VALUES EVP_SignInit_ex(), EVP_SignUpdate() and EVP_SignFinal() return 1 for success and 0 for failure. -EVP_PKEY_size() returns the maximum size of a signature in bytes. - The error codes can be obtained by L. -EVP_PKEY_security_bits() returns the number of security bits. - =head1 NOTES The B interface to digital signatures should almost always be used in @@ -95,6 +80,7 @@ The previous two bugs are fixed in the newer EVP_SignDigest*() function. =head1 SEE ALSO +L, L, L, L, L, L, L, L, diff --git a/util/missingcrypto.txt b/util/missingcrypto.txt index 7f1cf49ab3..954cfc4523 100644 --- a/util/missingcrypto.txt +++ b/util/missingcrypto.txt @@ -503,7 +503,6 @@ EVP_PKEY_add1_attr_by_NID(3) EVP_PKEY_add1_attr_by_OBJ(3) EVP_PKEY_add1_attr_by_txt(3) EVP_PKEY_assign(3) -EVP_PKEY_bits(3) EVP_PKEY_decrypt_old(3) EVP_PKEY_delete_attr(3) EVP_PKEY_encrypt_old(3) -- 2.25.1