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node_modules/crypto-es/lib/mode-ofb.js

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+import {
+  BlockCipherMode,
+} from './cipher-core.js';
+
+/**
+ * Output Feedback block mode.
+ */
+export class OFB extends BlockCipherMode {
+}
+OFB.Encryptor = class extends OFB {
+  processBlock(words, offset) {
+    const _words = words;
+
+    // Shortcuts
+    const cipher = this._cipher;
+    const { blockSize } = cipher;
+    const iv = this._iv;
+    let keystream = this._keystream;
+
+    // Generate keystream
+    if (iv) {
+      this._keystream = iv.slice(0);
+      keystream = this._keystream;
+
+      // Remove IV for subsequent blocks
+      this._iv = undefined;
+    }
+    cipher.encryptBlock(keystream, 0);
+
+    // Encrypt
+    for (let i = 0; i < blockSize; i += 1) {
+      _words[offset + i] ^= keystream[i];
+    }
+  }
+};
+OFB.Decryptor = OFB.Encryptor;