diff options
author | Richard Levitte <levitte@openssl.org> | 2020-01-08 11:04:15 +0100 |
---|---|---|
committer | Dr. Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com> | 2020-03-08 22:41:25 +0100 |
commit | eed9d03b4f6b7df80a34d274b551f48ae8295ef4 (patch) | |
tree | 718808099f1710d0b14149db66630d6eb17a021b /doc | |
parent | 9aba5c5ff2ccfe59e1c7d77918804919d549ebbc (diff) |
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 <nic.tuv@gmail.com>
(cherry picked from commit 6942a0d6feb8d3dcbbc6a1ec6be9de7ab2df1530)
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/11232)
Diffstat (limited to 'doc')
-rw-r--r-- | doc/man3/EVP_PKEY_size.pod | 80 | ||||
-rw-r--r-- | doc/man3/EVP_SignInit.pod | 24 |
2 files changed, 85 insertions, 19 deletions
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 <openssl/evp.h> + + 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<pkey>. +The primary documented use is with L<EVP_SignFinal(3)> and +L<EVP_SealInit(3)>, but it isn't limited there. The returned size is +also large enough for the output buffer of L<EVP_PKEY_sign(3)>, +L<EVP_PKEY_encrypt(3)>, L<EVP_PKEY_decrypt(3)>, L<EVP_PKEY_derive(3)>. + +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<EVP_PKEY_sign(3)> (the I<siglen> argument will +receive that length), to avoid bugs. + +EVP_PKEY_bits() returns the cryptographic length of the cryptosystem +to which the key in I<pkey> 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<pkey>, 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<EVP_DigestSignFinal(3)/NOTES>. + +=head1 SEE ALSO + +L<EVP_SignFinal(3)>, +L<EVP_SealInit(3)>, +L<EVP_PKEY_sign(3)>, +L<EVP_PKEY_encrypt(3)>, +L<EVP_PKEY_decrypt(3)>, +L<EVP_PKEY_derive(3)> + +=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<https://www.openssl.org/source/license.html>. + +=cut diff --git a/doc/man3/EVP_SignInit.pod b/doc/man3/EVP_SignInit.pod index c26b7f7d5d..65df4acfba 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<ctx>. This function can be called several times on the same B<ctx> to include additional data. EVP_SignFinal() signs the data in B<ctx> using the private key B<pkey> and -places the signature in B<sig>. B<sig> must be at least EVP_PKEY_size(pkey) +places the signature in B<sig>. B<sig> must be at least C<EVP_PKEY_size(pkey)> bytes in size. B<s> 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<s>, at most EVP_PKEY_size(pkey) bytes +will be written to the integer at B<s>, at most C<EVP_PKEY_size(pkey)> bytes will be written. EVP_SignInit() initializes a signing context B<ctx> to use the default implementation of digest B<type>. -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<pkey>, -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<ERR_get_error(3)>. -EVP_PKEY_security_bits() returns the number of security bits. - =head1 NOTES The B<EVP> 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<EVP_PKEY_size(3)>, L<EVP_PKEY_bits(3)>, L<EVP_PKEY_security_bits(3)>, L<EVP_VerifyInit(3)>, L<EVP_DigestInit(3)>, L<evp(7)>, L<HMAC(3)>, L<MD2(3)>, |