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/*
* Copyright (C) 2010 Andreas Steffen
* Hochschule fuer Technik Rapperswil
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*/
#include "pem_encoder.h"
#define BYTES_PER_LINE 48
/**
* See header.
*/
bool pem_encoder_encode(key_encoding_type_t type, chunk_t *encoding,
va_list args)
{
chunk_t asn1;
char *label;
u_char *pos;
size_t len, written, pem_chars, pem_lines;
switch (type)
{
case KEY_PUB_PEM:
if (!key_encoding_args(args, KEY_PART_RSA_PUB_ASN1_DER,
&asn1, KEY_PART_END))
{
return FALSE;
}
label ="PUBLIC KEY";
break;
case KEY_PRIV_PEM:
if (!key_encoding_args(args, KEY_PART_RSA_PRIV_ASN1_DER,
&asn1, KEY_PART_END))
{
return FALSE;
}
label ="RSA PRIVATE KEY";
break;
default:
return FALSE;
}
/* compute and allocate maximum size of PEM object */
pem_chars = 4*(asn1.len + 2)/3;
pem_lines = (asn1.len + BYTES_PER_LINE - 1) / BYTES_PER_LINE;
*encoding = chunk_alloc(5 + 2*(6 + strlen(label) + 6) + 3 + pem_chars + pem_lines);
pos = encoding->ptr;
len = encoding->len;
/* write PEM header */
written = snprintf(pos, len, "-----BEGIN %s-----\n", label);
pos += written;
len -= written;
/* write PEM body */
while (pem_lines--)
{
chunk_t asn1_line, pem_line;
asn1_line = chunk_create(asn1.ptr, min(asn1.len, BYTES_PER_LINE));
asn1.ptr += asn1_line.len;
asn1.len -= asn1_line.len;
pem_line = chunk_to_base64(asn1_line, pos);
pos += pem_line.len;
len -= pem_line.len;
*pos = '\n';
pos++;
len--;
}
/* write PEM trailer */
written = snprintf(pos, len, "-----END %s-----", label);
pos += written;
len -= written;
/* replace termination null character with newline */
*pos = '\n';
pos++;
len--;
/* compute effective length of PEM object */
encoding->len = pos - encoding->ptr;
return TRUE;
}
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