int PEM_get_EVP_CIPHER_INFO(char *header, EVP_CIPHER_INFO *cipher)
{
const EVP_CIPHER *enc = NULL;
char *p, c;
char **header_pp = &header;
cipher->cipher = NULL;
if ((header == NULL) || (*header == '\0') || (*header == '\n'))
return (1);
if (strncmp(header, "Proc-Type: ", 11) != 0) {
PEMerr(PEM_F_PEM_GET_EVP_CIPHER_INFO, PEM_R_NOT_PROC_TYPE);
return (0);
}
header += 11;
if (*header != '4')
return (0);
header++;
if (*header != ',')
return (0);
header++;
if (strncmp(header, "ENCRYPTED", 9) != 0) {
PEMerr(PEM_F_PEM_GET_EVP_CIPHER_INFO, PEM_R_NOT_ENCRYPTED);
return (0);
}
for (; (*header != '\n') && (*header != '\0'); header++) ;
if (*header == '\0') {
PEMerr(PEM_F_PEM_GET_EVP_CIPHER_INFO, PEM_R_SHORT_HEADER);
return (0);
}
header++;
if (strncmp(header, "DEK-Info: ", 10) != 0) {
PEMerr(PEM_F_PEM_GET_EVP_CIPHER_INFO, PEM_R_NOT_DEK_INFO);
return (0);
}
header += 10;
p = header;
for (;;) {
c = *header;
#ifndef CHARSET_EBCDIC
if (!(((c >= 'A') && (c <= 'Z')) || (c == '-') ||
((c >= '0') && (c <= '9'))))
break;
#else
if (!(isupper(c) || (c == '-') || isdigit(c)))
break;
#endif
header++;
}
*header = '\0';
cipher->cipher = enc = EVP_get_cipherbyname(p);
*header = c;
header++;
if (enc == NULL) {
PEMerr(PEM_F_PEM_GET_EVP_CIPHER_INFO, PEM_R_UNSUPPORTED_ENCRYPTION);
return (0);
}
if (!load_iv(header_pp, &(cipher->iv[0]), enc->iv_len))
return (0);
return (1);
}
/*
* This implements a very limited PEM header parser that does not support the
* full grammar of rfc1421. In particular, folded headers are not supported,
* nor is additional whitespace.
*
* A robust implementation would make use of a library that turns the headers
* into a BIO from which one folded line is read at a time, and is then split
* into a header label and content. We would then parse the content of the
* headers we care about. This is overkill for just this limited use-case, but
* presumably we also parse rfc822-style headers for S/MIME, so a common
* abstraction might well be more generally useful.
*/
int PEM_get_EVP_CIPHER_INFO(char *header, EVP_CIPHER_INFO *cipher)
{
static const char ProcType[] = "Proc-Type:";
static const char ENCRYPTED[] = "ENCRYPTED";
static const char DEKInfo[] = "DEK-Info:";
const EVP_CIPHER *enc = NULL;
int ivlen;
char *dekinfostart, c;
cipher->cipher = NULL;
if ((header == NULL) || (*header == '\0') || (*header == '\n'))
return 1;
if (strncmp(header, ProcType, sizeof(ProcType)-1) != 0) {
PEMerr(PEM_F_PEM_GET_EVP_CIPHER_INFO, PEM_R_NOT_PROC_TYPE);
return 0;
}
header += sizeof(ProcType)-1;
header += strspn(header, " \t");
if (*header++ != '4' || *header++ != ',')
return 0;
header += strspn(header, " \t");
/* We expect "ENCRYPTED" followed by optional white-space + line break */
if (strncmp(header, ENCRYPTED, sizeof(ENCRYPTED)-1) != 0 ||
strspn(header+sizeof(ENCRYPTED)-1, " \t\r\n") == 0) {
PEMerr(PEM_F_PEM_GET_EVP_CIPHER_INFO, PEM_R_NOT_ENCRYPTED);
return 0;
}
header += sizeof(ENCRYPTED)-1;
header += strspn(header, " \t\r");
if (*header++ != '\n') {
PEMerr(PEM_F_PEM_GET_EVP_CIPHER_INFO, PEM_R_SHORT_HEADER);
return 0;
}
/*-
* https://tools.ietf.org/html/rfc1421#section-4.6.1.3
* We expect "DEK-Info: algo[,hex-parameters]"
*/
if (strncmp(header, DEKInfo, sizeof(DEKInfo)-1) != 0) {
PEMerr(PEM_F_PEM_GET_EVP_CIPHER_INFO, PEM_R_NOT_DEK_INFO);
return 0;
}
header += sizeof(DEKInfo)-1;
header += strspn(header, " \t");
/*
* DEK-INFO is a comma-separated combination of algorithm name and optional
* parameters.
*/
dekinfostart = header;
header += strcspn(header, " \t,");
c = *header;
*header = '\0';
cipher->cipher = enc = EVP_get_cipherbyname(dekinfostart);
*header = c;
header += strspn(header, " \t");
if (enc == NULL) {
PEMerr(PEM_F_PEM_GET_EVP_CIPHER_INFO, PEM_R_UNSUPPORTED_ENCRYPTION);
return 0;
}
ivlen = EVP_CIPHER_iv_length(enc);
if (ivlen > 0 && *header++ != ',') {
PEMerr(PEM_F_PEM_GET_EVP_CIPHER_INFO, PEM_R_MISSING_DEK_IV);
return 0;
} else if (ivlen == 0 && *header == ',') {
PEMerr(PEM_F_PEM_GET_EVP_CIPHER_INFO, PEM_R_UNEXPECTED_DEK_IV);
return 0;
}
if (!load_iv(&header, cipher->iv, EVP_CIPHER_iv_length(enc)))
return 0;
return 1;
}
