OpenSSL: Asymmetric en- and decryption of a file


Hi,

this post describes the en- and decryption of a file with a asymmetric encryption algorithm.

Asymmetric encryption means you encrypt data by a public key and can only decrypt this data with a private key associated with the public key.
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OpenSSL: Symmetric en- and decryption of a file


Hi,

this post describes the en- and decryption of a file with a symmetric encryption algorithm.

Symmetric encryption means encryption and decryption is only possible with the same secret/password.
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VirtualBox: Changing the UUID of a VDI virtual disk File

Hi,

sometimes you simply want to copy a vdi file and attach it to another virtual machine.

This will fail because in a VirtualBox Installation each vdi Harddisk must have an unique UUID. This command line changes the UUID of a VDI file.
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Linux: Multiple ways to mount a partition in a disk image file

Hi,

there are several ways to mount a partition which is within a diskimage file created for example with dd.

The first and hard way  is to determine the offset of the partition start sector and mounting the disk by specifing the offset as parameter for the loop device.

You can use the  file or fdisk command to examine the file.
root@ubdev:/mnt/RaspberryPI # file 2012-07-15-wheezy-raspbian.img
2012-07-15-wheezy-raspbian.img: x86 boot sector; partition 1: ID=0xc, starthead 130, startsector 8192, 114688 sectors; partition 2: ID=0x83, starthead 165, startsector 122880, 3665920 sectors, code offset 0xb8

or

root@ubdev:/mnt/RaspberryPI # fdisk 2012-07-15-wheezy-raspbian.img

Command (m for help): p

Disk 2012-07-15-wheezy-raspbian.img: 1939 MB, 1939865600 bytes
255 heads, 63 sectors/track, 235 cylinders, total 3788800 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000714e9

Device Boot                               Start         End      Blocks   Id  System
2012-07-15-wheezy-raspbian.img1            8192      122879       57344    c  W95 FAT32 (LBA)
2012-07-15-wheezy-raspbian.img2          122880     3788799     1832960   83  Linux

For example the startsector of partition 2 is 122880,  this multiplied with the 512 bytes per sector is the byte offset of the partition. 122880*512=62914560.
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Windows: Error: Cannot read from the source file or disk, Could not find this item. This is no longer locate…

Hi,

difficult Windows issue today. A user had the problem that he could not delete a Folder (C:\Temp\orders) , also renaming or moving is not possible. The same behaviour with the command line tools rmdir, ren and move.
The folder was created from Excel with a vba macro.

Error message: Cannot read from source file or disk

Error message: Cannot read from source file or disk

The error message was: Cannot delete file: Cannot read from the source file or disk.
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