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Fix decryption of RC4-40 files.

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Michael R Sweet
2025-04-13 08:37:24 -04:00
parent 4219b8fd77
commit 20dd2a6d28
3 changed files with 28 additions and 11 deletions
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15
pdfio-value.c
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@@ -172,7 +172,7 @@ _pdfioValueDecrypt(pdfio_file_t *pdf, // I - PDF file
// Copy the decrypted string back to the value and adjust the length...
memcpy(v->value.binary.data, temp, templen);
if (pdf->encryption >= PDFIO_ENCRYPTION_AES_128)
if (pdf->encryption >= PDFIO_ENCRYPTION_AES_128 && temp[templen - 1] <= templen)
v->value.binary.datalen = templen - temp[templen - 1];
else
v->value.binary.datalen = templen;
@@ -183,17 +183,26 @@ _pdfioValueDecrypt(pdfio_file_t *pdf, // I - PDF file
case PDFIO_VALTYPE_STRING :
// Decrypt regular string...
templen = strlen(v->value.string);
if (templen > (sizeof(temp) - 33))
if (templen > (PDFIO_MAX_STRING - 1))
{
_pdfioFileError(pdf, "Unable to read encrypted string - too long.");
return (false);
}
else if ((temp = (uint8_t *)_pdfioStringAllocBuffer(pdf)) == NULL)
{
_pdfioFileError(pdf, "Unable to read encrypted binary string - out of memory.");
return (false);
}
ivlen = templen;
if ((cb = _pdfioCryptoMakeReader(pdf, obj, &ctx, (uint8_t *)v->value.string, &ivlen)) == NULL)
return (false);
templen = (cb)(&ctx, temp, (uint8_t *)v->value.string + ivlen, templen - ivlen);
if (pdf->encryption >= PDFIO_ENCRYPTION_AES_128 && temp[templen - 1] <= templen)
templen -= temp[templen - 1];
temp[templen] = '\0';
if ((timeval = get_date_time((char *)temp)) != 0)
@@ -207,6 +216,8 @@ _pdfioValueDecrypt(pdfio_file_t *pdf, // I - PDF file
// Copy the decrypted string back to the value...
v->value.string = pdfioStringCreate(pdf, (char *)temp);
}
_pdfioStringFreeBuffer(pdf, (char *)temp);
break;
}