> Source: [sk121515](https://support.checkpoint.com/results/sk/sk121515)

# sk121515 - ESP traffic dropped for "dropped by vpn_ipsec_decrypt Reason: Decryption failure" between Check Point gateway and 3rd party VPN peer when SHA-384 / SHA-512  is used 

| Property | Value |
|----------|-------|
| Solution ID | sk121515 |
| Date Created | 2017-11-23 |
| Last Modified | 2021-07-08 |
| Technical Level | General |
| Products | Security Gateway |
| Versions | R81 (EOS) |
| OS | Gaia |

## Symptoms

- * In the drops collected from the Check Point Security Gateway, can see that the ESP is dropped:

  ```
  
  ;[cpu_11];[fw_0];fw_log_drop: Packet proto=50 x.x.x.x:y -> x.x.x.x:y  dropped by vpn_ipsec_decrypt Reason: Decryption failure;
  ```

  <br />

* The SPI which is used by the affected connection is also seen in the VPND for "Authentication failure":

  ```
  
  [vpnd 31586 1983302304]@P-SR1-IFW1[7 Nov 15:00:44] CBinObjCommon::PackLogData: Field number:7, Data offset:15, Type:eFtCstring, Value:0xcd5faa59
  [vpnd 31586 1983302304]@P-SR1-IFW1[7 Nov 15:00:44] CBinObjCommon::PackLogData: Field number:8, Data offset:18, Type:eFtCstring, Value:Authentication failure. Sequence Number 1
  ```

  <br />

## Cause

SHA-384 / SHA-512 is used. Wrong digest calculations due to multiple CPUs accessing shared memory.

## Solution

This problem was fixed. The fix is included in:

* [**Check Point R81.10**](https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk170416)
* **[Jumbo Hotfix Accumulator for R81 - since Take_10](https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk170114&partition=Basic&product=All)**

Check Point recommends to always [upgrade to the most recent version](https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doShowproductpage&productTab=overview&product=446).  

<br />

**Related solution:** [sk104578 - VPN tunnel can not be established / no traffic passes when SHA-384 is configured for data integrity](https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk104578)

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