PKCS7_SIGNER_INFO: point out confusing names of digest_enc_alg and en…

…c_digest fields

Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from #22390)

(cherry picked from commit e15891b)

include/openssl/pkcs7.h.in

@@ -57,8 +57,8 @@ typedef struct pkcs7_signer_info_st {
     PKCS7_ISSUER_AND_SERIAL *issuer_and_serial;
     X509_ALGOR *digest_alg;
     STACK_OF(X509_ATTRIBUTE) *auth_attr; /* [ 0 ] */
-    X509_ALGOR *digest_enc_alg;
-    ASN1_OCTET_STRING *enc_digest;
+    X509_ALGOR *digest_enc_alg; /* confusing name, actually used for signing */
+    ASN1_OCTET_STRING *enc_digest; /* confusing name, actually signature */
     STACK_OF(X509_ATTRIBUTE) *unauth_attr; /* [ 1 ] */
     /* The private key to sign with */
     EVP_PKEY *pkey;