Implement support for AES encryption.

1 files changed, 73 insertions, 0 deletions

diff --git a/fitz/filt_aesd.c b/fitz/filt_aesd.c
new file mode 100644
index 00000000..63145bf1
--- /dev/null
+++ b/fitz/filt_aesd.c
@@ -0,0 +1,73 @@
+#include "fitz_base.h"
+#include "fitz_stream.h"
+
+typedef struct fz_aesd_s fz_aesd;
+
+struct fz_aesd_s
+{
+    fz_filter super;
+    fz_aes aes;
+    unsigned char iv[16];
+    int ivcount;
+};
+
+fz_error
+fz_newaesdfilter(fz_filter **fp, unsigned char *key, unsigned keylen)
+{
+    FZ_NEWFILTER(fz_aesd, f, aesdfilter);
+    aes_setkey_dec(&f->aes, key, keylen * 8);
+    f->ivcount = 0;
+    return fz_okay;
+}
+
+void
+fz_dropaesdfilter(fz_filter *f)
+{
+}
+
+fz_error
+fz_processaesdfilter(fz_filter *filter, fz_buffer *in, fz_buffer *out)
+{
+    fz_aesd *f = (fz_aesd*)filter;
+    int n;
+
+    while (1)
+    {
+	if (in->rp + 16 > in->wp)
+	{
+	    if (in->eof)
+		return fz_iodone;
+	    return fz_ioneedin;
+	}
+
+	if (f->ivcount < 16)
+	{
+	    f->iv[f->ivcount++] = *in->rp++;
+	}
+	else
+	{
+	    if (out->wp + 16 > out->ep)
+		return fz_ioneedout;
+
+	    n = MIN(in->wp - in->rp, out->ep - out->wp);
+	    if (n % 16 != 0)
+		return fz_throw("size of data to decrypt not a multiple of 16");
+	    if (n < 16)
+		return fz_throw("size of data to decrypt too small");
+
+	    aes_crypt_cbc(&f->aes, AES_DECRYPT, n, f->iv, in->rp, out->wp);
+	    in->rp += n;
+	    out->wp += n;
+
+	    /* Remove padding bytes */
+	    if (in->eof && in->rp == in->wp)
+	    {
+		int pad = out->wp[-1];
+		if (pad < 1 || pad > 16)
+		    return fz_throw("aes padding out of range: %d", pad);
+		out->wp -= pad;
+	    }
+	}
+    }
+}
+