1 files changed, 135 insertions, 0 deletions
diff --git a/lib/crypto-algorithms/base64.c b/lib/crypto-algorithms/base64.c
new file mode 100644
index 0000000..5e89808
--- /dev/null
+++ b/lib/crypto-algorithms/base64.c
@@ -0,0 +1,135 @@
+/*********************************************************************
+* Filename:   base64.c
+* Author:     Brad Conte (brad AT bradconte.com)
+* Copyright:
+* Disclaimer: This code is presented "as is" without any guarantees.
+* Details:    Implementation of the Base64 encoding algorithm.
+*********************************************************************/
+
+/*************************** HEADER FILES ***************************/
+#include <stdlib.h>
+#include "base64.h"
+
+/****************************** MACROS ******************************/
+#define NEWLINE_INVL 76
+
+/**************************** VARIABLES *****************************/
+// Note: To change the charset to a URL encoding, replace the '+' and '/' with '*' and '-'
+static const BYTE charset[]={"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"};
+
+/*********************** FUNCTION DEFINITIONS ***********************/
+BYTE revchar(char ch)
+{
+	if (ch >= 'A' && ch <= 'Z')
+		ch -= 'A';
+	else if (ch >= 'a' && ch <='z')
+		ch = ch - 'a' + 26;
+	else if (ch >= '0' && ch <='9')
+		ch = ch - '0' + 52;
+	else if (ch == '+')
+		ch = 62;
+	else if (ch == '/')
+		ch = 63;
+
+	return(ch);
+}
+
+size_t base64_encode(const BYTE in[], BYTE out[], size_t len, int newline_flag)
+{
+	size_t idx, idx2, blks, blk_ceiling, left_over, newline_count = 0;
+
+	blks = (len / 3);
+	left_over = len % 3;
+
+	if (out == NULL) {
+		idx2 = blks * 4 ;
+		if (left_over)
+			idx2 += 4;
+		if (newline_flag)
+			idx2 += len / 57;   // (NEWLINE_INVL / 4) * 3 = 57. One newline per 57 input bytes.
+	}
+	else {
+		// Since 3 input bytes = 4 output bytes, determine out how many even sets of
+		// 3 bytes the input has.
+		blk_ceiling = blks * 3;
+		for (idx = 0, idx2 = 0; idx < blk_ceiling; idx += 3, idx2 += 4) {
+			out[idx2]     = charset[in[idx] >> 2];
+			out[idx2 + 1] = charset[((in[idx] & 0x03) << 4) | (in[idx + 1] >> 4)];
+			out[idx2 + 2] = charset[((in[idx + 1] & 0x0f) << 2) | (in[idx + 2] >> 6)];
+			out[idx2 + 3] = charset[in[idx + 2] & 0x3F];
+			// The offical standard requires a newline every 76 characters.
+			// (Eg, first newline is character 77 of the output.)
+			if (((idx2 - newline_count + 4) % NEWLINE_INVL == 0) && newline_flag) {
+				out[idx2 + 4] = '\n';
+				idx2++;
+				newline_count++;
+			}
+		}
+
+		if (left_over == 1) {
+			out[idx2]     = charset[in[idx] >> 2];
+			out[idx2 + 1] = charset[(in[idx] & 0x03) << 4];
+			out[idx2 + 2] = '=';
+			out[idx2 + 3] = '=';
+			idx2 += 4;
+		}
+		else if (left_over == 2) {
+			out[idx2]     = charset[in[idx] >> 2];
+			out[idx2 + 1] = charset[((in[idx] & 0x03) << 4) | (in[idx + 1] >> 4)];
+			out[idx2 + 2] = charset[(in[idx + 1] & 0x0F) << 2];
+			out[idx2 + 3] = '=';
+			idx2 += 4;
+		}
+	}
+
+	return(idx2);
+}
+
+size_t base64_decode(const BYTE in[], BYTE out[], size_t len)
+{
+	BYTE ch;
+	size_t idx, idx2, blks, blk_ceiling, left_over;
+
+	if (in[len - 1] == '=')
+		len--;
+	if (in[len - 1] == '=')
+		len--;
+
+	blks = len / 4;
+	left_over = len % 4;
+
+	if (out == NULL) {
+		if (len >= 77 && in[NEWLINE_INVL] == '\n')   // Verify that newlines where used.
+			len -= len / (NEWLINE_INVL + 1);
+		blks = len / 4;
+		left_over = len % 4;
+
+		idx = blks * 3;
+		if (left_over == 2)
+			idx ++;
+		else if (left_over == 3)
+			idx += 2;
+	}
+	else {
+		blk_ceiling = blks * 4;
+		for (idx = 0, idx2 = 0; idx2 < blk_ceiling; idx += 3, idx2 += 4) {
+			if (in[idx2] == '\n')
+				idx2++;
+			out[idx]     = (revchar(in[idx2]) << 2) | ((revchar(in[idx2 + 1]) & 0x30) >> 4);
+			out[idx + 1] = (revchar(in[idx2 + 1]) << 4) | (revchar(in[idx2 + 2]) >> 2);
+			out[idx + 2] = (revchar(in[idx2 + 2]) << 6) | revchar(in[idx2 + 3]);
+		}
+
+		if (left_over == 2) {
+			out[idx]     = (revchar(in[idx2]) << 2) | ((revchar(in[idx2 + 1]) & 0x30) >> 4);
+			idx++;
+		}
+		else if (left_over == 3) {
+			out[idx]     = (revchar(in[idx2]) << 2) | ((revchar(in[idx2 + 1]) & 0x30) >> 4);
+			out[idx + 1] = (revchar(in[idx2 + 1]) << 4) | (revchar(in[idx2 + 2]) >> 2);
+			idx += 2;
+		}
+	}
+
+	return(idx);
+}