diff --git a/src/core/base64.c b/src/core/base64.c
new file mode 100644
index 00000000..e54821e3
--- /dev/null
+++ b/src/core/base64.c
@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2009 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * 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 any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <stdint.h>
+#include <string.h>
+#include <assert.h>
+#include <gpxe/base64.h>
+
+/** @file
+ *
+ * Base64 encoding
+ *
+ */
+
+static const char base64[64] =
+	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+/**
+ * Base64-encode a string
+ *
+ * @v raw		Raw string
+ * @v encoded		Buffer for encoded string
+ *
+ * The buffer must be the correct length for the encoded string.  Use
+ * something like
+ *
+ *     char buf[ base64_encoded_len ( strlen ( raw ) ) + 1 ];
+ *
+ * (the +1 is for the terminating NUL) to provide a buffer of the
+ * correct size.
+ */
+void base64_encode ( const char *raw, char *encoded ) {
+	const uint8_t *raw_bytes = ( ( const uint8_t * ) raw );
+	uint8_t *encoded_bytes = ( ( uint8_t * ) encoded );
+	size_t raw_bit_len = ( 8 * strlen ( raw ) );
+	unsigned int bit;
+	unsigned int tmp;
+
+	for ( bit = 0 ; bit < raw_bit_len ; bit += 6 ) {
+		tmp = ( ( raw_bytes[ bit / 8 ] << ( bit % 8 ) ) |
+			( raw_bytes[ bit / 8 + 1 ] >> ( 8 - ( bit % 8 ) ) ) );
+		tmp = ( ( tmp >> 2 ) & 0x3f );
+		*(encoded_bytes++) = base64[tmp];
+	}
+	for ( ; ( bit % 8 ) != 0 ; bit += 6 )
+		*(encoded_bytes++) = '=';
+	*(encoded_bytes++) = '\0';
+
+	DBG ( "Base64-encoded \"%s\" as \"%s\"\n", raw, encoded );
+	assert ( strlen ( encoded ) == base64_encoded_len ( strlen ( raw ) ) );
+}
diff --git a/src/include/gpxe/base64.h b/src/include/gpxe/base64.h
new file mode 100644
index 00000000..3321971a
--- /dev/null
+++ b/src/include/gpxe/base64.h
@@ -0,0 +1,24 @@
+#ifndef _GPXE_BASE64_H
+#define _GPXE_BASE64_H
+
+/** @file
+ *
+ * Base64 encoding
+ *
+ */
+
+#include <stdint.h>
+
+/**
+ * Calculate length of base64-encoded string
+ *
+ * @v raw_len		Raw string length (excluding NUL)
+ * @ret encoded_len	Encoded string length (excluding NUL)
+ */
+static inline size_t base64_encoded_len ( size_t raw_len ) {
+	return ( ( ( raw_len + 3 - 1 ) / 3 ) * 4 );
+}
+
+extern void base64_encode ( const char *raw, char *encoded );
+
+#endif /* _GPXE_BASE64_H */