---
title: "CRYPT_GEN_RANDOM (Transact-SQL) | Microsoft Docs"
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---
# CRYPT_GEN_RANDOM (Transact-SQL)
[!INCLUDE[tsql-appliesto-ss2008-asdb-xxxx-xxx-md](../../includes/tsql-appliesto-ss2008-asdb-xxxx-xxx-md.md)]

This function returns a cryptographic, randomly-generated number, generated by the Crypto API (CAPI). `CRYPT_GEN_RANDOM` returns a hexadecimal number with a length of a specified number of bytes.
  
![Topic link icon](../../database-engine/configure-windows/media/topic-link.gif "Topic link icon") [Transact-SQL Syntax Conventions](../../t-sql/language-elements/transact-sql-syntax-conventions-transact-sql.md)
  
## Syntax  
  
```sql
CRYPT_GEN_RANDOM ( length [ , seed ] )   
```  
  
## Arguments  
*length*  
The length, in bytes, of the number that `CRYPT_GEN_RANDOM` will create. The *length* argument has an **int** data type, and a value range between 1 and 8000. `CRYPT_GEN_RANDOM` returns NULL for an **int** value outside this range. 
  
*seed*  
An optional hexadecimal number, for use as a random seed value. The length of *seed* must match the value of the *length* argument. The *seed* argument has a **varbinary(8000)** data type.
  
## Returned Types  
**varbinary(8000)**
  
## Permissions  
This function is public and it does not require any special permissions.
  
## Examples  
  
### A. Generating a random number  
This example generates a random number of length 50 bytes:
  
```sql
SELECT CRYPT_GEN_RANDOM(50) ;  
```  
  
This example generates a random number of length 4 bytes, using a 4-byte seed:
  
```sql
SELECT CRYPT_GEN_RANDOM(4, 0x25F18060) ;  
```  
  
## See also
[RAND (Transact-SQL)](../../t-sql/functions/rand-transact-sql.md)