1# Converting SM2 Signature Formats (ArkTS) 2 3<!--Kit: Crypto Architecture Kit--> 4<!--Subsystem: Security--> 5<!--Owner: @zxz--3--> 6<!--Designer: @lanming--> 7<!--Tester: @PAFT--> 8<!--Adviser: @zengyawen--> 9 10HarmonyOS supports the conversion between the DER and R|S formats. 11You can specify SM2 signature parameters and convert them to DER ciphertext. You can also extract SM2 signature data from DER ciphertext. 12 13**Converting Ciphertext Parameters to DER Ciphertext** 141. Create an [EccSignatureSpec](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#eccsignaturespec20) instance to specify SM2 ciphertext parameters. 15 162. Call [genEccSignature](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#geneccsignature20) to pass the **EccSignatureSpec** object to convert it to SM2 ciphertext in DER format. 17 18```ts 19import { cryptoFramework } from '@kit.CryptoArchitectureKit'; 20import { BusinessError } from '@kit.BasicServicesKit'; 21 22function testGenEccSignature() { 23 try { 24 let spec: cryptoFramework.EccSignatureSpec = { 25 r: BigInt('97726608965854271693043443511967021777934035174185659091642456228829830775155'), 26 s: BigInt('23084224202834231287427338597254751764391338275617140205467537273296855150376'), 27 }; 28 29 let data = cryptoFramework.SignatureUtils.genEccSignature(spec); 30 console.info('genEccSignature success'); 31 console.info('data is ' + data); 32 } catch (err) { 33 let e: BusinessError = err as BusinessError; 34 console.error(`ecc error, ${e.code}, ${e.message}`); 35 } 36} 37``` 38 39**Converting DER Ciphertext to the R and S Parameters** 401. Specifies the SM2 ciphertext parameters in DER format. 41 422. Call [genEccSignatureSpec](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#geneccsignaturespec20) to pass data in DER format and convert the data into SM2 ciphertext in R|S format. 43 44```ts 45import { cryptoFramework } from '@kit.CryptoArchitectureKit'; 46import { BusinessError } from '@kit.BasicServicesKit'; 47 48function testGenEccSignatureSpec() { 49 try { 50 let data = 51 new Uint8Array([48, 69, 2, 33, 0, 216, 15, 76, 238, 158, 165, 108, 76, 72, 63, 115, 52, 255, 51, 149, 54, 224, 52 179, 49, 225, 70, 36, 117, 88, 154, 154, 27, 194, 161, 3, 1, 115, 2, 32, 51, 9, 53, 55, 248, 82, 7, 159, 179, 53 144, 57, 151, 195, 17, 31, 106, 123, 32, 139, 219, 6, 253, 62, 240, 181, 134, 214, 107, 27, 230, 175, 40]); 54 let spec: cryptoFramework.EccSignatureSpec = cryptoFramework.SignatureUtils.genEccSignatureSpec(data); 55 console.info('genEccSignatureSpec success'); 56 } catch (err) { 57 let e: BusinessError = err as BusinessError; 58 console.error(`ecc error, ${e.code}, ${e.message}`); 59 } 60} 61``` 62