Manual Pages for UNIX Operating System command usage for man PKCS7_verify

OpenSSL                                    PKCS7_verify(3openssl)



NNNNAAAAMMMMEEEE
     PKCS7_verify - verify a PKCS#7 signedData structure

SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
      #include 

      int PKCS7_verify(PKCS7 *p7, STACK_OF(X509) *certs, X509_STORE *store, BIO *indata, BIO *out, int flags);

      STACK_OF(X509) *PKCS7_get0_signers(PKCS7 *p7, STACK_OF(X509) *certs, int flags);


DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
     PKCS7_verify() verifies a PKCS#7 signedData structure. pppp7777 is
     the PKCS7 structure to verify. cccceeeerrrrttttssss is a set of
     certificates in which to search for the signer's
     certificate. ssssttttoooorrrreeee is a trusted certficate store (used for
     chain verification). iiiinnnnddddaaaattttaaaa is the signed data if the
     content is not present in pppp7777 (that is it is detached). The
     content is written to oooouuuutttt if it is not NULL.

     ffffllllaaaaggggssss is an optional set of flags, which can be used to
     modify the verify operation.

     PKCS7_get0_signers() retrieves the signer's certificates
     from pppp7777, it does nnnnooootttt check their validity or whether any
     signatures are valid. The cccceeeerrrrttttssss and ffffllllaaaaggggssss parameters have
     the same meanings as in PKCS7_verify().

VVVVEEEERRRRIIIIFFFFYYYY PPPPRRRROOOOCCCCEEEESSSSSSSS
     Normally the verify process proceeds as follows.

     Initially some sanity checks are performed on pppp7777. The type
     of pppp7777 must be signedData. There must be at least one
     signature on the data and if the content is detached iiiinnnnddddaaaattttaaaa
     cannot be NNNNUUUULLLLLLLL.

     An attempt is made to locate all the signer's certificates,
     first looking in the cccceeeerrrrttttssss parameter (if it is not NNNNUUUULLLLLLLL) and
     then looking in any certificates contained in the pppp7777
     structure itself. If any signer's certificates cannot be
     located the operation fails.

     Each signer's certificate is chain verified using the
     ssssmmmmiiiimmmmeeeessssiiiiggggnnnn purpose and the supplied trusted certificate
     store. Any internal certificates in the message are used as
     untrusted CAs. If any chain verify fails an error code is
     returned.

     Finally the signed content is read (and written to oooouuuutttt is it
     is not NULL) and the signature's checked.





27/Mar/2010            Last change: 0.9.8o                      1






OpenSSL                                    PKCS7_verify(3openssl)



     If all signature's verify correctly then the function is
     successful.

     Any of the following flags (ored together) can be passed in
     the ffffllllaaaaggggssss parameter to change the default verify behaviour.
     Only the flag PPPPKKKKCCCCSSSS7777_NNNNOOOOIIIINNNNTTTTEEEERRRRNNNN is meaningful to
     PKCS7_get0_signers().

     If PPPPKKKKCCCCSSSS7777_NNNNOOOOIIIINNNNTTTTEEEERRRRNNNN is set the certificates in the message
     itself are not searched when locating the signer's
     certificate. This means that all the signers certificates
     must be in the cccceeeerrrrttttssss parameter.

     If the PPPPKKKKCCCCSSSS7777_TTTTEEEEXXXXTTTT flag is set MIME headers for type
     tttteeeexxxxtttt////ppppllllaaaaiiiinnnn are deleted from the content. If the content is
     not of type tttteeeexxxxtttt////ppppllllaaaaiiiinnnn then an error is returned.

     If PPPPKKKKCCCCSSSS7777_NNNNOOOOVVVVEEEERRRRIIIIFFFFYYYY is set the signer's certificates are not
     chain verified.

     If PPPPKKKKCCCCSSSS7777_NNNNOOOOCCCCHHHHAAAAIIIINNNN is set then the certificates contained in
     the message are not used as untrusted CAs. This means that
     the whole verify chain (apart from the signer's certificate)
     must be contained in the trusted store.

     If PPPPKKKKCCCCSSSS7777_NNNNOOOOSSSSIIIIGGGGSSSS is set then the signatures on the data are
     not checked.

NNNNOOOOTTTTEEEESSSS
     One application of PPPPKKKKCCCCSSSS7777_NNNNOOOOIIIINNNNTTTTEEEERRRRNNNN is to only accept messages
     signed by a small number of certificates. The acceptable
     certificates would be passed in the cccceeeerrrrttttssss parameter. In this
     case if the signer is not one of the certificates supplied
     in cccceeeerrrrttttssss then the verify will fail because the signer cannot
     be found.

     Care should be taken when modifying the default verify
     behaviour, for example setting PPPPKKKKCCCCSSSS7777_NNNNOOOOVVVVEEEERRRRIIIIFFFFYYYY||||PPPPKKKKCCCCSSSS7777_NNNNOOOOSSSSIIIIGGGGSSSS
     will totally disable all verification and any signed message
     will be considered valid. This combination is however useful
     if one merely wishes to write the content to oooouuuutttt and its
     validity is not considered important.

     Chain verification should arguably be performed  using the
     signing time rather than the current time. However since the
     signing time is supplied by the signer it cannot be trusted
     without additional evidence (such as a trusted timestamp).

RRRREEEETTTTUUUURRRRNNNN VVVVAAAALLLLUUUUEEEESSSS
     PKCS7_verify() returns 1 for a successful verification and
     zero or a negative value if an error occurs.




27/Mar/2010            Last change: 0.9.8o                      2






OpenSSL                                    PKCS7_verify(3openssl)



     PKCS7_get0_signers() returns all signers or NNNNUUUULLLLLLLL if an error
     occurred.

     The error can be obtained from ERR_get_error(3)

BBBBUUUUGGGGSSSS
     The trusted certificate store is not searched for the
     signers certificate, this is primarily due to the
     inadequacies of the current XXXX555500009999_SSSSTTTTOOOORRRREEEE functionality.

     The lack of single pass processing and need to hold all data
     in memory as mentioned in PKCS7_sign() also applies to
     PKCS7_verify().

SSSSEEEEEEEE AAAALLLLSSSSOOOO
     ERR_get_error(3), PKCS7_sign(3)

HHHHIIIISSSSTTTTOOOORRRRYYYY
     PKCS7_verify() was added to OpenSSL 0.9.5




































27/Mar/2010            Last change: 0.9.8o                      3