// Copyright (c) Microsoft Corporation.
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// Licensed under the MIT License.
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/**
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* @internal
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* Encodes a length of a packet in DER format
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*/
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function encodeLength(length) {
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if (length <= 127) {
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return Uint8Array.of(length);
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}
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else if (length < 256) {
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return Uint8Array.of(0x81, length);
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}
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else if (length < 65536) {
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return Uint8Array.of(0x82, length >> 8, length & 0xff);
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}
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else {
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throw new Error("Unsupported length to encode");
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}
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}
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/**
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* @internal
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* Encodes a buffer for DER, as sets the id to the given id
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*/
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function encodeBuffer(buffer, bufferId) {
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if (buffer.length === 0) {
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return buffer;
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}
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let result = new Uint8Array(buffer);
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// If the high bit is set, prepend a 0
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if (result[0] & 0x80) {
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const array = new Uint8Array(result.length + 1);
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array[0] = 0;
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array.set(result, 1);
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result = array;
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}
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// Prepend the DER header for this buffer
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const encodedLength = encodeLength(result.length);
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const totalLength = 1 + encodedLength.length + result.length;
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const outputBuffer = new Uint8Array(totalLength);
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outputBuffer[0] = bufferId;
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outputBuffer.set(encodedLength, 1);
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outputBuffer.set(result, 1 + encodedLength.length);
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return outputBuffer;
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}
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function makeSequence(encodedParts) {
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const totalLength = encodedParts.reduce((sum, part) => sum + part.length, 0);
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const sequence = new Uint8Array(totalLength);
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for (let i = 0; i < encodedParts.length; i++) {
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const previousLength = i > 0 ? encodedParts[i - 1].length : 0;
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sequence.set(encodedParts[i], previousLength);
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}
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const full_encoded = encodeBuffer(sequence, 0x30); // SEQUENCE
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return Buffer.from(full_encoded).toString("base64");
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}
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/**
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* Fill in the PEM with 64 character lines as per RFC:
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*
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* "To represent the encapsulated text of a PEM message, the encoding
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* function's output is delimited into text lines (using local
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* conventions), with each line except the last containing exactly 64
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* printable characters and the final line containing 64 or fewer
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* printable characters."
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*/
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function formatBase64Sequence(base64Sequence) {
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const lines = base64Sequence.match(/.{1,64}/g);
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let result = "";
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if (lines) {
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for (const line of lines) {
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result += line;
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result += "\n";
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}
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}
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else {
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throw new Error("Could not create correct PEM");
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}
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return result;
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}
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/**
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* @internal
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* Encode a JWK to PEM format. To do so, it internally repackages the JWK as a DER
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* that is then encoded as a PEM.
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*/
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export function convertJWKtoPEM(key) {
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let result = "";
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if (key.n && key.e) {
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const parts = [key.n, key.e];
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const encodedParts = parts.map((part) => encodeBuffer(part, 0x2)); // INTEGER
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const base64Sequence = makeSequence(encodedParts);
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result += "-----BEGIN RSA PUBLIC KEY-----\n";
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result += formatBase64Sequence(base64Sequence);
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result += "-----END RSA PUBLIC KEY-----\n";
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}
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if (!result.length) {
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throw new Error("Unsupported key format for local operations");
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}
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return result.slice(0, -1); // Removing the last new line
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}
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//# sourceMappingURL=conversions.js.map
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