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jsowell-pile/src/main/java/com/jsowell/wxpay/utils/AesUtil.java

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+package com.jsowell.wxpay.utils;
+
+import javax.crypto.Cipher;
+import javax.crypto.NoSuchPaddingException;
+import javax.crypto.spec.GCMParameterSpec;
+import javax.crypto.spec.SecretKeySpec;
+import java.io.IOException;
+import java.security.GeneralSecurityException;
+import java.security.InvalidAlgorithmParameterException;
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
+import java.util.Base64;
+
+public class AesUtil {
+
+	static final int KEY_LENGTH_BYTE = 32;
+	static final int TAG_LENGTH_BIT = 128;
+	private final byte[] aesKey;
+
+	public AesUtil(byte[] key) {
+		if (key.length != KEY_LENGTH_BYTE) {
+			throw new IllegalArgumentException("无效的ApiV3Key，长度必须为32个字节");
+		}
+		this.aesKey = key;
+	}
+
+	public String decryptToString(byte[] associatedData, byte[] nonce, String ciphertext)
+			throws GeneralSecurityException, IOException {
+		try {
+			Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
+
+			SecretKeySpec key = new SecretKeySpec(aesKey, "AES");
+			GCMParameterSpec spec = new GCMParameterSpec(TAG_LENGTH_BIT, nonce);
+
+			cipher.init(Cipher.DECRYPT_MODE, key, spec);
+			cipher.updateAAD(associatedData);
+
+			return new String(cipher.doFinal(Base64.getDecoder().decode(ciphertext)), "utf-8");
+		} catch (NoSuchAlgorithmException | NoSuchPaddingException e) {
+			throw new IllegalStateException(e);
+		} catch (InvalidKeyException | InvalidAlgorithmParameterException e) {
+			throw new IllegalArgumentException(e);
+		}
+	}
+}