Fix pkeyutl/rsautl empty encrypt-input/decrypt-output handling

[openssl.git] / doc / apps / pkeyutl.pod

diff --git a/doc/apps/pkeyutl.pod b/doc/apps/pkeyutl.pod
index a7b75e6c756d7a03e372ef2ff18d1c31ca6420ab..d44f73aeecc71ddeffa432ce08bd4b1fb2829e77 100644 (file)
--- a/doc/apps/pkeyutl.pod
+++ b/doc/apps/pkeyutl.pod
@@ -11,10 +11,10 @@ B<openssl> B<pkeyutl>
 [B<-out file>]
 [B<-sigfile file>]
 [B<-inkey file>]
-[B<-keyform PEM|DER>]
+[B<-keyform PEM|DER|ENGINE>]
 [B<-passin arg>]
 [B<-peerkey file>]
-[B<-peerform PEM|DER>]
+[B<-peerform PEM|DER|ENGINE>]
 [B<-pubin>]
 [B<-certin>]
 [B<-rev>]
@@ -52,7 +52,7 @@ default.
 
 the input key file, by default it should be a private key.
 
-=item B<-keyform PEM|DER>
+=item B<-keyform PEM|DER|ENGINE>
 
 the key format PEM, DER or ENGINE.
 
@@ -66,7 +66,7 @@ see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
 
 the peer key file, used by key derivation (agreement) operations.
 
-=item B<-peerform PEM|DER>
+=item B<-peerform PEM|DER|ENGINE>
 
 the peer key format PEM, DER or ENGINE.
 
@@ -137,6 +137,19 @@ Unless otherwise mentioned all algorithms support the B<digest:alg> option
 which specifies the digest in use for sign, verify and verifyrecover operations.
 The value B<alg> should represent a digest name as used in the
 EVP_get_digestbyname() function for example B<sha1>.
+This value is used only for sanity-checking the lengths of data passed in to
+the B<pkeyutl> and for creating the structures that make up the signature
+(e.g. B<DigestInfo> in RSASSA PKCS#1 v1.5 signatures).
+In case of RSA, ECDSA and DSA signatures, this utility
+will not perform hashing on input data but rather use the data directly as
+input of signature algorithm. Depending on key type, signature type and mode
+of padding, the maximum acceptable lengths of input data differ. In general,
+with RSA the signed data can't be longer than the key modulus, in case of ECDSA
+and DSA the data shouldn't be longer than field size, otherwise it will be
+silently truncated to field size.
+
+In other words, if the value of digest is B<sha1> the input should be 20 bytes
+long binary encoding of SHA-1 hash function output.
 
 =head1 RSA ALGORITHM